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JOURNAL OF THE LEPIDOPTEPISTS' SOCIETY
Volume 25 Supplement 3
1IOLOGICAL STUDIES ON MOTHS OF THE GENUS
ETHMIA IN CALIFORNIA
(Ge1ech i o i dea)
Je rry A . Powe1 1 University of California, Berkeley
Table of Contents
Introduction.......................3
Techniques ........................ h
Acknowledgements ..................... 7
Ethmia ooquillettella (Busck) .............. 8
E. scylla Powell.....................12
E. bvevistriga bvevistriga Clarke............17
E. b. avdicola Powell ..................20
E. albitogata Walsingham.................22
E. plagiobothrae Powell .................25
E. minuta Powel1.....................30
E. charybdis Powell ...................31
E. albistrigella (Walsingham) ..............35
E. nadia Clarke.....................38
E, semilugens (Zel ler)..................hO
E. arotostaphylella (Walsingham).............hi
E, disoostrigella (Chambers)...............^6
E. semitenebvella Dyar..................51
E. ti-mberlakei Powell ..................53
Literature Cited.....................56
Index to host plants...................57
Illustrations......................58
3
INTRODUCTION1
The family Ethmiidae is composed of small to moderate sized moths and is world-wide in distribution, with its greatest diversity occurring in the Neotropical Region. Consisting primarily of the one large genus Ethmia the group is distinct in many respects, without close relationship to other families. Ethmiids have in the past been considered as related to or members of the Oecophoridae. Probably they are most closely related to the Stenomidae, and the three groups are considered to be families in the Gelechioidea by present workers.
About 30 members of the genus Ethmia have been reared previously, primarily in the Palearctic and in the eastern United States. Nearly all feed externally on Boraginaceae or Hydrophy11aceae during the larval stage, but there have been few detailed studies. Habits of the few other Nearctic genera are equally poorly known: species in Pyrami dob el a feed on Penstemon (Scrophulariaceae) and Buddleia (Logani-aceae) (Braun, 1921; Keifer, 1936), while the biology of Pseudethmia is unknown. Two other species formerly considered to be ethm \ \ ds, Eumeyrickia trimacule11 a (Fitch) and "Ethmia" ooloradella (Wa1singham) , are fungus feeders and have recently been transferred to the Oecophoridae, a group containing genera with similar morphological and biological traits (Lawrence and Powell, 1969) .
In connection with a California Insect Survey project on Ethmiidae, I began to investigate the biologies of these moths in 1961. The study gradually developed into a comprehensive taxonomic one encompassing the New World fauna, some 135 species. Field efforts were particularly directed towards Ethmia in California, resulting in the present data on \h species, which, however, represent only a few species groups in one section of the genus. Thus it seems appropriate to give this detailed biological information separately from the systematic treatment of the genus as a whole. A general review of biological knowledge for the family is given in that study (Powell, 1971).
It became evident early in this work that some species are diurnal and others nocturnal. It was one of the aims of the investigation to clearly define which are diurnal in order to assess the significance of this phase of the moths1 biology in systematic relationships. Adults of both diurnal and nocturnal species are sometimes encountered in numbers during the daytime, and at times it is difficult to distinguish between active flight behavior and reactionary movement in response to disturbance by the observer. There-
1 This study was in part made possible through assistance from National Science Foundation Grants GB-4014 and GB-68l3x, "Comparative biology in relation to systematics of Microlepidoptera", 1965-1970.
k
I n t rodu ct i on
fore, criteria I have used for defining natural activity rhythm in the diel cycle have been the timing of mating, oviposition, and the "quiescent posture" by moths in captivity.
The resting posture during periods of activity was distinguishable from that shown by moths in the "quiescent posture" assumed during the inactive phase of the diel cycle. In the "quiescent posture" the wings were tightly clasped against the abdomen and the antennae were held back alongside the body, under the costal edges of the wings. The insects crouched low, almost appressed to the substrate, with the legs widely outstretched. Moths temporarily not moving during activity periods held the wings somewhat loosely spread from the sides of the abdomen, and the antennae projected outward, at right angles to the body axis or somewhat forward, usually moving slowly. At the same time they stood up higher above the substrate with the legs less widely outstretched,
The "quiescent posture" was exhibited at night by all individuals of species which mate and oviposit in daytime. There was not a temperature correlation with darkness, since heating indoors kept the temperature above 18° C until midnight or so, while it often remained as low as 12° during the early daylight hours.
As a result of this study, it is now known that diurnal species possess small eyes and usually very dark integument and vestiture. Thus the behavior pattern can be predicted on the basis of preserved specimens. The eye size has been quantified and described elsewhere (Powell, 1971). In a few species the eyes are intermediate in size, and my observations on Ethmia avctostaphylella suggest that this is correlated with a tendency towards crepuscular behavior,
Techniques
The present data originate from field collections of either late instar larvae or adults which were retained alive for oviposition. The moths were taken at lights or by netting them during daytime or at dusk. Adults were transported from the field in cotton-stoppered glass vials and were caged in one-gallon glass breeding jars. The housing methods and details of the container were essential 1y the same as used and described in studies of tortricine moths (Powell, 1964). The jars proved more satisfactory for ethmiids than for Tortricinae because oviposition by Kthmia usually occurred.on the host plant or on the nylon mesh used as a ceiling on the cage (figs. 11, 12), rather than on the sides of the glass container. Insofar as possible the jars were placed adjacent to an open window, exposed to natural lighting, including direct, dappled sunlight (filtered through tree foliage) during part of the day. Observations after nightfall were made by means of a flashlight provided with a cover of red construction paper. This light source usually did not attract or otherwise disturb the moths.
Biological studies on Ethmia
5
In the field larvae were generally detected by hand-searching suspect plants. A few species could be effectively collected by beating (certain perennial plants) or sweeping, but most of the present species live in concealed shelters on low, herbaceous hosts. Larvae were transported from the field in polyethylene bags and generally were housed in closed containers with cut sprigs of host plant. Newly hatched larvae in the laboratory were usually housed in 25 x 100 mm salve tins on small bouquets of foodplant in water vials plugged by cotton. In few cases greenhouse plants were used for early instar establishment. Larger larvae were housed in plastic sandwich boxes or 85 x 100 mm jars with cuttings of foodplant.
To provide fresh plant material for species reared from eggs, plants from the collection site were transplanted to pots in a greenhouse, bouquets were placed in water, or cuttings of the same or a closely related plant were obtained from the University of California, Berkeley, Botanical Garden at the time of egg hatch. Transplanting (perennial Phacelia) or cuttings in water (annuals) proved satisfactory for early instars since these plants usually persisted well for 2-3 weeks. However they matured in advance of field conditions, and later instars were provided with plants from the Botanical Garden unless the original collection site could be revisited conveniently. For field collected late instar larvae, cuttings were either offered as bouquets in water or were refrigerated (± *» ° C) and later offered without water. This required frequent replenishing of provisions.
Soft paper toweling, folded many times, and sometimes cut sections of dry Yucca whiyplei floral stalks were provided as pupation substrates. A tendency to wander and burrow into soft bark and similar substances has been reported in the literature for several Ethmia.
Rearing was conducted at laboratory temperatures (usually varying about 12-20° daily). Pupae in diapause were in some cases housed in an outdoor screen cage at Berkeley or in an open shed at Russell Property, near Lafayette, California, an inland station where greater climatic extremes more approximate field conditions of inland parts of California.
The only previous biological information concerning the species discussed below is the report by Dyar (1902) that E. semitenebrella had been reared from Cercocarpus in Arizona. Hosts of three species must have been known to Keifer (1936) who described the pupa of albitogata and mentioned larval characters of two other species, but he gave no information on their biologies. Therefore I attempted to discover the host association through observing moths in the field. Adults of both diurnal and nocturnal species tend to stay close to the larval foodplants, and each of the present species has proven to be specific to members of one plant genus so far as known. Following field collection, I caged females with a small bouquet of the suspect host. If no clear association had been ascertained, a varied menu of
6
In t roduct i on
possible oviposition substrates was offered. Females exhibited only a poor oviposition response or none at all, if caged without the appropriate host. The fact that most previous recorded plants for Ethmia are Boraginaceae and Hydrophy11aceae helped to restrict my selection, during field searches. However, in one case this restricted thinking hindered the eventual discovery of an unrelated plant as the host.
Detailed comparison of eggs was not attempted. Photographs showing general habitus and placement on the plant were taken for most species. High magnification scanning electron micrographs were executed only for scylla- In scheduling for photography eggs were usually stored in a refrigerator (k° C) for several days, which delayed maturation of developing larvae for a period about equal to that in cold storage.
When sufficient numbers were available, larvae representing each instar were preserved, using KAAD for a few minutes, followed by storage in 95% ethyl alcohol. Head capsules representing previous instars of living individuals were recovered and were used in measurements for estimating the number of instars, along with the preserved 1 a rvae.
Detailed morphological descriptions of the larval stages have not been made. The larvae are briefly characterized, with special reference to instar differences, following the biological discussion of each species. Abbreviations are as follows (see fig. 7): H_C_ = Head Capsule, a measurement of maximum Width as seen from above is given; ThSh = Prothoracic Shield; P i n = Pinacula; D_ = Dorsal band a narrow color stripe in later instars of most species, from pro- or mesothorax to ninth abdominal segment; £L_ = Dorsolateral pigment bands lateral to D_, above the spiracles; L_ = Lateral band, a broad area around and below spiracles; LV = Lateroventra1 band, a weakly developed pigment band below L_, above the legs; AbdC r = Abdominal Crotchets, an extended mesoseries or mesopene11 ipse in all the present species; AnC r = Anal Crotchets. All measurements were made through a disc micrometer at 27x or 5^x magnification and are given in mm, based on specimens distended in KAAD. Measurements are based on six or more specimens except where indicated otherwise, with the number in brackets [ ]. Color features were noted from living larvae. Integumental colors of Ethmia fade during preservation.
Morphological characteristics of the pupae are variable, and only limited comparison between species is attempted owing to inadequte series for most species. Most of the species examined here are quite similar.
Biological studies on Ethmia
7
Constant Biological Characters
Several features of the biology and behavior appear to be consistent among all species, and these are not discussed for each species. The eggs are deposited singly, cemented to the substrate by an affixed area nearly as long and wide as the egg. The egg is more or less rectangular in outline, nearly as thick as wide; it does not flatten out onto the subs,trate, but conforms to minor irregularities, sometimes altering its shape a little (e.g., fig. 12). At hatching larvae chew a round, ragged hole at the micropylar end, sometimes well off center. The hole is about one-half the diameter of the egg, and no further feeding is done on the eggshell by newly hatched larvae. When disturbed or dislodged, larvae of most species, especially in later instars, react by wriggling violently backward. A few species feign death and fall, immobile, to the substrate. Based on head capsule measurements, there appear to be five instars in several species, but data are too fragmentary to determine the number with certainty for most species. At least in brevistriga and scylla, and probably plagiobothrae and albi-togata, there are five, while large species such as discos-trigella and arotostaphylella probably undergo six, at least in some individuals (figs. 1-6). At maturity larvae of probably all species wander, often having been found to burrow into soft, woody substrates to pupate. Data on specimens I have examined, especially of several species reared by F.D. Parker at the University of California, Davis, from trap nests' , indicate this is a widespread habit. During my study larvae usually were confined in salve tins or 35mm pill boxes for pupation, and most did not burrow into yucca pith, using unnatural situations such as a corner of the container. At emergence the pupal shell remains inside the cocoon, held in place by the hooked setae of the anteriorly directed "anal legs" (figs. 8, 9) (in all species except soylla). The cremaster such as is normally developed in most Lepidoptera at the tip of the abdomen is vestigial. Eight frail setae are present in a constant arrangement for all species, but these do not aid in anchoring the pupa. The degree to which the "anal legs" of the pupa are appressed to the abdominal venter or angled outward varies within species, possibly affected by the shape of the cocoon.
Acknowledgements
Grateful acknowledgement is made to Helen K. Sharsmith, formerly of the University of California, Berkeley, Herbarium, who provided many of the plant identifications associa-
1 Sections of Sambuous stems, 45 cm in length, which had been stuck into the ground, with a 1.5-4 mm hole drilled in the exposed end (Parker and Bohart, 1966).
8
ooquillettella
ted with this study. Through Mrs. Sharsmith, Lincoln Constance, University of California, Berkeley., determined most of tPie Phaoelia, and Franc la Chisaki Hommersand, Chapel Hill, No/th. Carolina, identified some of the Amsinokia species. Thanks are due Anton Crist and other personnel of the University of California Botanical Garden, who have been cooperative in providing cuttings of native host plants many times during the past decade. Photographs of eggs in situ were executed by A.A. Blaker, Scientific Photographic Laboratory, University of California, Berkeley. Stereoscan Scanning Electron Microphotographs were executed through the cooperation of T.E. Everhart, Electronics Research Laboratory, University of California, Berkeley, through support from National Science Foundation Grant G B-6 4 2 8 and Grant No. GM1553 6 from the National Institutes of Health. Assistance with field collections, particularly during early years of the study, was given by several persons, whose help is appreciated and acknowledged by mention in the text; but special thanks are due C. Don MacNeill, Oakland Museum, and Catharine Toschi Tauber, Ithaca, New York. Where not otherwise indicated, all collections and observations are my own.
ETHMIA COQUILLETTELLA BUSCK
Ethmia coquillettella Busck, 1907, Proc. Ent. Soc. Wash., 8:95.
This species has been collected at only a few widely scattered sites in arid parts of California and interior British Columbia during the 70 years since the original specimens were taken in the vicinity of Los Angeles (Powell, 1959, 1971). Considerable interpopulational variation is exhibited, and study of more material will be necessary in order to confirm that just one species is involved. This and related species in the southwestern United States, which have the palpi clothed with stiff, erect bristles, are believed to be diurnal.
I have not been able to confi rm the foodplant of coquillettella with certainty. The moths have been encountered only in small numbers, and not in close association with any plant. Larvae accept Phaoelia and Nemophila in the laboratory, and on two occasions have been reared to the fifth instar but not to maturity. One larva was collected in the field on Phaoelia distans .
Study a reas: - l)Pinyon Flat, 16 road miles southwest of Palm Desert, Riverside Co.; 1 male, 3 females taken in flight, 11:00 A.M. - 1:00 P.M., April 13, 1963 (C.A. Toschi and J. Powell), 3 females retained alive (6 3 D 19) - 2) Railroad Canyon, k miles northeast of Elsinore, Riverside Co.; 1 male, 2 females at flowers of Coreopsis califovnica (Com-positae), 11:45 A.M. - 2:00 P.M., April 13, 1965 (C.A. Toschi and J. Powell), 2 females retained alive (6 5 D1 ) . 3) Del Puerto Canyon, 23 road miles west of Patterson, Stan-
Biological studies on Ethmia
9
islaus Co.; h males, 1 female taken in flight, 12:30 - 3:00 P.M., March 25, 1969, 2 males, 1 female retained alive (69C9M; 1 larva on Fhaoelia distanq, April 27, 1969 (69D59) . At Pinyon Flat the moths were taken near Mentzelia (Loas-aceae), a possible nectar source, and immature Fhaoelia distans var. australis; at Railroad Canyon a mixed stand of Fhaoelia cioutaria var. hispida3 P. distans, and Nemophila menziesii grew near the collection site; while at Del Puerto Canyon, Fhaoelia distans and Amsinckia intermedia were suspect hos ts .
A d u 1 t be hav i^o^r : - Collection records indicate a single flight period in early spring, in California from mid February to mid April, varying with conditions of locality and season. Laboratory observations have been sporadic but tend to confirm the diurnal behavior pattern indicated by adult morpBology and field collections. In the breeding jar moths were active during the day and occasionally at night if dCrect lighting was on them. Mating was not observed.
Females from pfnyon Flat were caged with Fhaoelia and Mentzelia t'n a 85 x 100 mm jar, but on the day following collection the jar became water soaked during transport in a field ice box. Two of the females recovered and were transferred to a one-gallon jar; but probably they had been weakened as it appeared that neither left the floor of the container. Only 9 eggs were deposited, on the cardboard jar floor.
Females from Railroad Canyon were also housed in an 85 x 100 mm jar under field conditions. A bouquet of Fhaoelia cioutaria, Nemophila* and a Coreopsis flower was offered as possible oviposition substrate and nectar source. A natural photoperiod rhythm was not provided, and, with exposure to indirect and direct lighting late in the evenings, activity periods apparently were irregular. A total of k0 eqgs was deposited by one or both females, in part during early hours of night (8:00 P.M. - 2:00 A.M.) and during early morning hours (2:00 A.M. - 8:00 A.M.). A few eggs were place on Leaves of Nemophila but most were deposited around corners of the container floor.
The adults from Del Puerto Canyon were caged in more suitable conditions, in a one-gallon breeding jar provided with a bouquet of immature Fhaoelia distanss Amsinckia in flower, and immature Epilobium sp. (Onagraceae) , housed in natural photoperiod. Males lived only 1-3 days, but the females survided 10 days, depositing 70 eggs, nearly all during the first two days of confinement. Both sexes were inactive at night, remaining in quiescent posture until 10:00 - 11:00 A.M. The period of highest activity appeared to be 1:00 - 3:00 P.M., although individual movement occurred in dappled sunlight until 6:00 P.M. The moths displayed a stronger positive phototropic response than some other diurnal species. Oviposition was observed between 1:30 and 3:00 P.M., and a few eggs were deposited later in the day. The female selected roughened surfaces in the side of the
10
coquiltettell a
jar towards the light. She walked about on undersides of Phaoelia leaves and on the nylon screen ceiling with the abdomen extended and curled downward, probing at the substrate. Usually she ran a few "steps", then probed two or three times, sometimes slightly to the side. A quiescent pause of several seconds followed each egg deposition.
Of the 70 eggs, about 75% were deposited around the s side of the jar towards the light; and of the total, 60% were placed on the masking tape around the floor and 15% on the nylon. Only 8 eggs were deposited on the plants, all on the undersides of Fhaoelia leaves adjacent to the light side.
Egg. - Eggs were uniformly subrectangu1 ar, varying from 0.46 x 0.76 to 0.M x 0.82 mm in outline. During development all turned pink by the third day, and a somewhat darker reddish by the 7th to 9th day. Incubation time varied from 10 days in April in the field (65DI) to 11-12 days in March at room temperatures (69C94). Emergence sometimes occurred well off center of the micropylar end.
La rva , - Considerable difficulty was encountered in inducing young larvae to establish and feed, relative to my experience with other Ethmia. A distinct preference for flower buds was shown, and it appeared that leaves were unsuitable for development. A continuous supply of immature flowers was not provided, and this may have been a critical factor in the failure of larvae to reach maturity under laboratory conditions.
First instar larvae (63DIO) placed on Thaoelia distans from Pinyon Flat which had been/in refrigeration 16 days failed to survive. Some fed a little at the base of buds, but none successfully established themselves.
One and two day old larvae (6 5 D1) were placed on fresh buds of Nemophila maculata and Phacetia tanacet-ifolia from the Botanical Garden; larvae at first began feeding on both plants, either in the buds or in crotches of leaflets or sepals. All eight larvae placed on the immature, scorpioid spikes of the Phacelia established successfully and reached at least the second instar. The inflorescences were tightly curled, and by the second day frass was visible between the appressed, hirsute buds. Larvae continued to feed inside the buds during the first 12 days; on May 7, 10 day old plant material from the Botanical Garden was added when the larvae were 11-12 days old. Three days later only three larvae had moved to the more recently offered buds. On May lA, the 3rd and 4th instar larvae were moved to fresh Phaoelia tanaoeti-folia from the Botanical Garden. By this time the plants had bloomed and subsequent feeding took place mainly on smaller leaflets, often those adjoining flowers.
The ephemeral character of the Nemophila flowers prevented establishment of all but one of the first instar larvae.
Biological studies on Ethmia
1 1
This larva succeeded in burrowing into an unopened bud, preventing it from further development, and fed on the pistil and stamens for 11 days; it then migrated to a new, less developed bud and began feeding. The 15 day, 3rd instar larva left the Nemophila (which was partially collapsing in the water vial) and was transferred to the Phacelia • At the Botanical Garden the Nemophila was drying by the time the larvae were 19-20 days old, which, together with the difficulties encountered in establishing on this plant, suggests that Nemophila is not a suitable host. Nutritionally the Nemophila flowers appeared to be adequate since the one larva was as mature as the most advanced of those feeding on Phacelia at each inspection.
On May 2k , about 30 days after hatching, laboratory observations were interrupted by a vacation camping trip. The remaining larvae were carried in a salve tin and were subjected to greater temperature fluctuations than in the laboratory and to drying of the foodplant. Fresh Phacelia leaves were added from San Bernardino County, California, and Coconino County, Arizona, but the final larva died by June k while an early fifth instar.
Unfed first instar larvae (69C9M were placed on Phacelia distans from Del Puerto Canyon, which had been kept in water 12-13 days; establishment was affected by burrowing into unopened buds. After k days an accumulation of fine frass was noted in the dense hairs of the inflorescence. On April 19, the 10-12 day old 2nd and 3rd instar larvae were transferred within their shelters to vials with fresh Nemophila menziesii from Santa Clara County. Although the original Phacelia had become blackened and mouldy, after 3 days there were no signs of feeding on either flowers or leaves of the Nemophila . The 13—15 day old, 3rd instar larvae were then offered fresh Phacelia tanacetifolia from the Botanical Garden, and all established new shelters. Subsequent feeding occurred in buds on bouquets of this host. Fresh sprigs were added every few days, as it did not keep well in water, and two exposures to badly withered plants probably affected larval development. Owing to a field trip intervention, surveillance was terminated on May 9, and the 30-32 day old larvae were preserved. They apparently were penultimate and immature last instar individuals which had not grown during the preceding k days due to the condition of the plant.
Inspection of Phacelia distans at Del Puerto Canyon on April 27 (when laboratory larvae were about three weeks old) revealed only one larva of coquillet tell a* This individual was provided P. distans for 8 days, then P. tanacetifolia. However, foodplant conditions were intermittently poor, and the larva died on May 7 in the final instar.
Since feeding took place on buds of Phacelia tanaceti-folia in water and the developmental rate was similar to
12
scylla
that of Ethmia brevistriga, it is assumed that P. distansand P. cicutaria might serve as suitable hosts at the study sites. However, as with other species in the diurnal group, a definite preference for feeding in unopened flowers was shown, and it may be that fresh buds are necessary to provide sufficient nourishment to complete development.
First instar: Length 1.6 mm; HC_ o.20-0.22 mm, brown,ocel-lar area black; ThSh brownish; integument and setae unpig-mented.
Second instar: Length [1] 4.0 mm; HC_ [4] 0.30-0.35 mm, brown, frontal area slightly paler; ThSh, thoracic legs, lateral spots on prolegs, and anal shield, brown; Pin minute, dark, integument otherwise unpigmented. AbdCr 8-10; AnCr 7-8.
Third instar .-none preserved; HC_ and ThSh dark brown, integument pattern pale purplish.
Fourth instar: Length [2] 8.2-8.5 mm; H_C [3] 0.67-0.74 mm, brown, mottled with pale areas; ThSh mottled, brown with darker spots; Pin blackish; D_ white (not unpigmented) with thin, median deep ochreous streaks; DL^ mottled, pale purplish to brownish olive, large, distinct white rings encircling pinacula; AbdCr 7-10 (usually 8-9); AnCr 7-8.
Fifth instar: [5] Length 8.0-12.0 mm (none mature); HC_ 0.74-0.82 mm, markings strongly contrasted; integument colors similar to penultimate, ThSh brown with darker spots; D and pinacula rings of DL more contrastingly white, DL_, DV darker purplish or olive, L slightly whitish or unpigmented, with or without faint ochreous streak; AbdCr 9-14 (usually 12-14) ; AnCr 11-12.
Ethmia scylla Powell
Ethmia scylla Powell, 1971, U. Calif. Publ . Ent., in press.
Three localities along the inner Coast Range of central California comprise the known range of soyl'la. I collected the first specimen on March 18, 1959, at about the time my review of the poor state of knowledge of Ethmia in California had gone to press (Powell, 1959). However, exactly ten years were to elapse before I was able to solve the mystery of scylla's biology, the search having been hampered by a preconceived notion that some Borage or Hydrophyll must be the hostplant. Although the adults resemble Ethmia brevistriga, and thus might be expected to feed on a Fhacelia, this species proves to be unique as the only member of the genus known to use Scrophu1 ariaceae and further the only member of a Nearctic or Holarctic species group which does not possess the peculiar "anal legs" of the pupa.
Study a rea s. - l)Russelmann Park, north slope of Mt.
Biological studies on Ethmia
13
Diablo, 1100 feet, Contra Costa Co.; adults numerous, April 2, I960 (J.M. Burns and J. Powell); adults sparse, April 6, 1962, 3 males, 2 females retained alive (62D2). 2) Raines Park, Del Puerto Canyon, Stanislaus Co.; adults sparse, March 5, 1963, (R. Langston and J. Powell), k males, 2 females retained alive (6 3 C1) ; negative results checking Am-sinokia intermedia, April 30, 1963; adults abundant, March 19, 1969, 4 males, 3 females retained alive (69C90); adults common, March 25, 1969, 2 females retained alive (69C90); larvae abundant in flowers Collinsia heterophylla April 27, 1969 (69D60). 3) Three miles northwest of Rumsey, Yolo Co.; adults sparse, March 8, 196*+.
Adult behavior. - The species has a single annual flight, in moderately early spring, from late February to early April, varying two to three weeks with seasonal conditions. This is well ahead of the bloom period of the foodplant. All three localities are deciduous oak-digger pine scrub forest situations. At Russelmann Park the moths appeared to fly around poison oak, Rhus diversiloba, in the manner of Ethmia albitogata at the San Bruno Mountains, where Am-sinckia grows in close association with the poison oak clumps. Adults of scylla sometimes perched on poison oak foliage where they resemble bird droppings. The association at Raines Park proved to be a general one; the Collinsia is abundant in semi-shaded spots on north slopes around various shrub growth including Juniperus. , Arctostaphylos , and Ceanothus .
Adults were observed in the field between 11:00 A.M. and 4:00 P.M. Two mating pairs were taken, one at 3 : 40 P.M. on April 2, i960. Mating did not occur in the laboratory.
In captivity moths intermittently abandoned the quiescent posture between 8:30 and 10:30 A.M., but continuous activity did not begin before 11:00. It lasted until about 4:00 P.M., after which movement gradually subsided, ceasing by 5:45 or 6:00 P.M., at about sunset. As indicated by ovi-position, the height of activity was not concentrated into a brief period and did not strongly vary between cloudy and clear days, extending from 12:00 or 1:00 P.M. to about 4:00. Generally adults were strongly positively phototropic, and oviposition by the 1962 females seemed to corroborate this. However, when Collinsia was offered (69C90), eggs were more evenly distributed, with more than half of those deposited on plants having been placed on a Collinsia in the center of the jar, rather than on those nearer the light source.
In earlier collections various immature, low growing annual plants from the collection sites were included in the breeding jars. The 1962 lot was also provided with a few small Plagiobothrys nothofulvus from Lake County. Several small Amsinokia intermedia in bloom were included in the 1963 trial. One or more of the 62D2 females deposited 5 eggs on the nylon ceiling and 30 on the cardboard floor (which was roughened, with fibres protruding, the result of
u
scylla
removal of masking tape), 80% concentrated on the side of the jar towards the light. In experiments with other Eth-mia the cardboard floor was sometimes used by old, weak females, but in this case it was selected on the first day of confinement, judging from the incubation period.
The 1969 moths were offered an array of Amsinokia in early bloom, and immature plants of both Phaoelia distans and Collinsia hetevoiphylla. The latter had been observed in high numerical density in the vicinity of female moth concentration. In the breeding jar females complied by displaying a distinct selection not only for Collinsia, but for the leaf axils. A total of \2h eggs was deposited by k females; exactly half were placed on the nylon screen, while nearly all the remainder (60) were laid in leaf axils of Collinsia. Most were on the upperside of the petioles, but some were placed in axils where secondary leaves originated, so that they were sometimes affixed to undersides of secondary petioles when tucked into the primary axils. They were distributed along the height of the plant, but tended to be concentrated (60%) on the middle axils, which bore the secondary leaf growth. One egg was deposited on the upperside of a leaf blade. One was deposited on each of the Amsinokia and Phaoelia.
Females tended to concentrate on the screen ceiling towards the light source, but wandered during oviposition. The probing action of the extended ovipositor was more or less continuous at about 30/minute. One female was observed in this behavior on the nylon, traveling some 7 cm during 2.5 minutes; finally after k minutes she extruded an egg onto the apparently uniform nylon mesh. Deposition of an egg required 1-2 seconds, after which the female usually quickly moved several cm without probing the ovipositor, then stopped in a stationary pause, sometimes moving to the light side to do so. Results of individual female's efforts were not tabulated, but 3 females deposited a combined total of about 100 eggs in 2 days.
The moths did not survive long under cage conditions, males living 3"7 days, and the females only 3~5 days.
Egg . - (figs. 13—17) The egg is characteristically elongate, cylindrical, with the chorion strongly reticulated with ridges which bear no microstructura1 modifications. Eggs varied from 0.30 x 0.59 mm to 0.27 x 0.61 mm.
During development the eggs changed color, to pale orange by the 2nd day, bright pink by the 3rd day, and gradually darker reddish before the larvae became visible prior to emergence. Incubation required 10 days (62D2) and 8-9 days (69C90) at laboratory temperatures.
L_a_r_y_a_. - In order to confirm the host selection displayed in oviposition behavior, separate lots of newly hatched larvae (69C90) were segregated in 32 x 90 mm shell vials and were offered cut terminals including flower buds,
Biological studies on Ethmia
15
of four menus: a) Collinsia heterophylla alone, b) Phacelia distans and Amsinokia intermedia, c) Collinsia and Phacelia d) Collinsia and Amsinokia • Six larvae were isolated in each vial, and three additional larvae were added to c) and d) after three days. In each case the only successful establishment occurred in flower buds of Collinsia* with about 33% of the individuals successful. The Amsinokia did not fare well under the conditions and was essentially wilted within three days, while the Phacelia remained in good condition for at least five days. All plants were in poor condition by eight days, and the a) vial became diseased by the 11th day. There was no evidence that feeding occurred on either Collinsia leaves or any part of the Phacelia or Amsinokia. Surviving larvae, along with others established in separate containers with Collinsia bouquets were fed subsequently on flowers of Collinsia heterophylla which had been taken in immature condition on March 25 at Raines Park and kept in water, where the plants developed to full bloom. Additional C. heterophylla from the Botanical Garden was provided to nearly mature, 2*1-26 day old larvae.
Larvae of all ins tars fed within developing flowers. If a bud was entered, no feeding occurred on sepals except in excavating an entrance hole; ovaries, stamens, and corolla parts were fed upon, preventing the bud from opening. Usually partially or fully opened flowers were used, and ovaries were consumed, along with basal portions of the corolla, but no feeding occurred on the sepals. After a few days young larvae migrated to new flowers, leaving the wilted corolla in situ* In the field this resulted in several withered and abandoned flowers on a given plant, indicating the presence of one larva. Normally only one or two flowers on any given tier were affected. The larva moved upward as the inflorescence elongated, rather than workinq around the inflorescence until all available flowers at one tier level we re exh au s ted.
In contrast to some species of Ethmia* the larvae curled and feigned death at the slightest disturbance. They were thus difficult to manipulate during transfer from one flower to another, as they could not be induced to spin silk onto the probe, and even if transferred with a damp brush or forceps and balanced in an immobile posture on a new flower, would almost always drop off upon moving again. However, they showed a strong tendency to wander up vertical objects, and usually migrated back up flower stems and reestablished on their own when a given flower became exhausted.
Development proceded rapidly relative to other Ethmia. Individuals provided with Collinsia buds in good condition reached the second instar by 8-10 days, and the third in-star by 11-13 days. The fourth instar was not preserved, but all larvae had passed through it by 25-27 days. Final instar, 25~29 day old larvae were preserved on April 25 and 27, and the last mature larva prepared for pupation on April 29, 31 days following beginning of egg hatch.
16
scy I la
On April 2 7 the Raines Park site was revisited and larvae were found abundantly in Collinsia flowers (69D60). Development was retarded relative to that in the laboratoty. No larvae were preserved on this date, but after six days storage at outdoor temperatures, a larval sample showed three instars, 3rd, 4th, 5th, in a 2: 4: 5: ratio. At eight days all three were still present, in the ratio 1: 3- 10. Only full grown larvae remained on May 9 (12 days after collection), 51 days following the original collection of females in the field. Thus height of oviposition probably occurred March 19 ~ 2 6, and most larvae reached maturity in the field about May 3~9, an average lapse of 45 days.
There are five clear-cut larval instars, according to unsexed head capsule measurements (fig 4).
First instar: Length 1.2-1.4 mm; HC^ 0.16-0.18 mm, light brown; ThSh narrowly light brown, well defined; body yellowish, integument unpigmented.
Second instar: Length 2.0-2.5 mm; HC 0.25-0.27 mm, dark brown; ThSh well defined, brown; integument with pale PL color, faintly defined paler D and rings around Pin which are barely visible; AbCr 8-9, essentially a complete circle; AnCr 7-8.
Third instar: Length 3-2-4.8 mm; HC 0.38-0.43 mm, dark brown, slightly mottled paler; ThSh brown, slightly mottled darker posteriorly; D well defined; unpigmented except slight median pink line; E^L pink, weakly defined; LV pinkish, scarcely defined; Pin dark, well defined; AbdCr 9-11; AnCr 8-9-
Fourth instar: Length 5.5-7-2 mm; HC_ 0.51-0.68 mm, light brownish mottled with darker brown; integument pattern as in final instar, paler; D_ well defined, unpigmented except median pinkish line; DL fairly well defined; Pin black, surrounded by unpigmented circles; AbdCr 10-14 (mostly 10-11); AnCr 8-9-
Fifth instar: Length 8.8-12.0 mm; HC_ 0.82-0.98 mm, orange with faint brown mottling; ThSh sclerotized as median lateral spot and posterolateral blackish patch; integument pattern well defined pink on whitish-unpigmented or purplish on pinkish-unpigmented (probably varying with petal colors consumed), D well defined with median pink streak; E^L well defined, dark, defining unpigmented circles around the black Pin, L unpigmented; LV fairly well defined; AbdCr 14-18, rarely 20, usually nearly uniordial; AnCr 16-17; one or two secondary setae in LV group on abdominal segments 1, 2, 7, sometimes 8.
Pupa. - Smal1 blocks of dry Yucca whipplei floral stalks were provided and were used by all successfully pupating individuals. Each spun the cocoon in a narrow gallery running parallel with the grain of the wood. It
Biological studies on Ethmia
17
appeared that abandoned Cossonus galleries were appropriated and at times somewhat enlarged. Emergence trackways led out to split ends of the substrate and each was divided into two chambers by silken caps, one near the surface and one recessed several mm, which was of slightly less diameter than the pupation chamber, located at the anterior end of the cocoon. Cocoons ranged about 5.4-5-7 x 1.3-1.7 mm and were simple, without any interior meshwork.
Pupae (fig. 10) ranged 4.7-5.2 mm in length and were simple, without functional cremaster, anal legs, or other setation. The ninth segment was unmodified and fused to the eighth at mid venter. The spiracles were small, simple, 0.35 mm in diameter. Evidently the cocoon shape retains the pupa at emergence.
Pupae formed by larvae in May, 1969, failed to emerge, although housed at Russell shed, where conditions stimulated emergence of plagiobothrae (69D58) in the same winter. Pupae were still viable appearing when extracted from cocoons after 17 mon t hs.
Ethmia brevistriga brevistriga Clarke
Ethmia brevistriga Clarke, 1950, Jour. Wash. Acad. Sci., 40:163.
The nominotypic subspecies is known only from localities along the immediate coast of California.
Study a rea s . - 1) Laguna Puerca, San Francisco; adults common in association with Phaoelia distans, April 7, 1961; 5 males, 5 females retained alive (C.D. MacNeill and J. Powell) (61D2); larvae on P. distans, May 6, 1961 (61D2); larvae on P. distans, May 24, 1961 (61E21). 2) Lobos Creek, San Francisco; adults in association with P. distans , April 7, 1961 ; 1 male, 1 female retained alive (61D 2) .
Adult behav i o r. - A single, well defined flight was shown in 196O and 1961 at San Francisco, from mid March to mid April, prior to beginning of flowering of Phaoelia distans. Six pairs were caged with a bouquet of P. distans. These moths showed a slightly later diurnal activity period than albitogata, housed under similar conditions. Individuals of brevistriga were not active before noon, and even by 1:30 P.M. only limited movement and no oviposition was occurring. The height of activity appeared around 3:30 to 4:30, continuing until about sunset, around 6:00 P.M. By 7:00 they had become sluggish and only flew straight down if dislodged. None moved at night. This species showed a greater tendency to perch on the host plant than any of the others studied. About 60-80% of the individuals rested on the plant, even at night.
Mating was witnessed twice. A pair was swept in copulo
18
bvevistviga
at Lobos Creek at 3:00 P.M. They had been flying or were perched on the tip of a Phacelia branch. They were still in coition at 7:00 P.M. following transport from the field. Housed in darkness, they remained in oopulo until at least 11:00 P.M. The second pair mated sometime between 1:00 and 5:30 P.M. on the first day after confinement; after 5:30 they remained inactive, clinging to an upright pin all night. Separation occurred between 9:30 and 10:10 A.M.
Oviposition by several females was observed, between 3:30 and 4:00 P.M. It probably took place earlier, and one female exhibited apparent oviposition behavior at 5:15 P.M. Characteristically females crawled over the uppermost foliage or moved spirally up a stem, with the abdomen distended, moving rather slowly and vibrating their antennae. The substrate was tapped 4 or 5 times with the papillae anales prior to deposition of an egg. A period of quiescence (18 to 45 seconds) usually followed each egg after which the moth resumed its crawling or flew to a new spot. Periods of crawling on the screen were sometimes interspersed with those of oviposition.
About 80 eggs were deposited by the females during the first two days of confinement. It appeared that none were laid on the plant after the third day. Nearly all were concentrated in the upper 5 cm of foliage, mostly around the buds. The eggs on the inflorescences were not nested deeply into crevices, but were placed between the plant hairs (figs. 21-23)- The uppersides of upper, young leaves and the main stem were also used as oviposition sites. Eggs placed below the upper 5 cm of fol iage were on the stem. None were placed on the undersides of the leaves except on the main midrib. Some oviposition after the third or fourth day of confinement took place on the cardboard floor of the jar.
Egg . - The eggs ranged 0.31 x 0.53 mm to 0.30 x 0.60 mm and as thick as wide (fig. 23). When first deposited they were pearly white; after about 48 hours they turned yellow. Prior to hatching the dark larval head capsule became visible. Eggs hatched April 19-20, after about 11 days at room temperature.
Larva . - Several Phacelia distans plants from Laguna Puerca were planted in pots in a greenhouse prior to emergence of the first instar larvae. These plants, which matured sooner than those in the field, were used for observations on behavior of young larvae.
First instar larvae migrated upward and commenced feeding at bases of flower buds. In one instance a one day old larva had bored through the sepals of a small unopened bud. The first external evidence of established larvae appeared by 4-6 days in the form of small frass accumulations in the f1 owe r heads .
By the 14 th day the insectary plants had bloomed com-
Biological studies on Ethmia
19
pletely, but the larvae, in the third and fourth instars, had prevented development of some buds in which they fed. In each case the larva had formed a well concealed shelter between the rows of flowers on the scorpioid spike, hidden primarily by the dense plant hairs. The shelters were held together by a weak network of silk. Feeding occurred in the currently opened flowers and unopened buds, usually all the way out to the terminal end of the inflorescence. Not all of every flower was consumed, and some were still in apparent bloom. Damage to the inflorescence was not evident externally, and the frass accumulations were the only visible evidence of the larvae.
On May 5, 17 days after commencement of hatching in the laboratory, the Laguna Puerca site was investigated. Three third instar larvae were found, in shelters similar to, but less extensive than, those in the greenhouse. Field plants had bloomed only about half way along the inflorescence. Larvae were located just basad of the current bloom, feeding on the flowers with developing seed. Frass from these shelters was not visible from the exterior, evidently having been dispersed by factors such as wind. All larvae were moved to newly potted plants at this time, but the plants did not survive. The remaining larvae were transferred to salve tins with cut inflorescences two days later.
By the 24th or 25th day following hatching some larvae had reached the last instar. One larva on one of the original potted plants reached the last instar by the 28th day, when it was preserved.
A third examination of the field colony was made on May 24, 36 days after laboratory eggs began hatching and 6 days after the first cocoon was spun in the greenhouse. Larvae were found to be fairly common in areas where the Phacelia was more sparse, although the shelters were as inconcpicuous as they had been three weeks earlier. By this time field larvae were mostly penultimate instar; a few were antepenultimate, and only one was in the final instar.
All larvae reached the final instar by the eighth day after the second larval collection, and the final larvae which had not spun cocoons were preserved June 6, 60 days after the original adult collection.
There appeared to be five instars, on the basis of un-sexed head capsule measurements (fig. 3).
First instar: Length 1.5-1.7 mm; HC_ .0 .18-0 . 20 mm, brown; ThSh and anal shield pale brown; integument and setae unplgmented.
Second instar: None preserved; HC_ 0.27-0.36 mm [5], brown.
20
brevistriga
Third instar: Length 4.3-6.0 mm [3]; HC 0.42-0.47 mm, dark brown; ThSh brown; Pin minute, dark; DL sometimes with a trace of pale brownish, AbdCr 8-11; AnCr 9.
Fourth instar: Length 5.3-9-3 mm; HC_ 0.66-0.77 mm, usually slightly to considerably paler brown than third in-star, lightly mottled; ThSh paler brown; Pin small; integu-mental pigment well developed, D white, DL brownish, broad, extending below spiracle; L narrow, whitish; LV with little pigment; AbdCr 9-13; AnCr 9-10.
Fifth instar: Length 9.0-13.2 mm; HC_ 0.86-0.95 mm, orange brown, mottled; ThSh pale brown with dark spots; D white (not unpigmented), DL broad, as in fourth instar, darker, purplish; Pin small, in DL_ surrounded by whitish circles; L white; AbdCr 15"l8; AnCr 16-17. Segment A9 with 6-8 tiny secondary setae on LV.
P upa. - Pupation and successful development took place in small beetle galleries in split sections of Yucca whipplei inflorescence stalk, in one instance about 15 mm into the yucca, although not much excavation of the matrix by the Ethmia larvae was involved. Pupation also occurred in a corner of a salve tin, in flower heads, and in folds of paper toweling. The only successful emergence occurred from one of the latter. Those in the flowers and salve tin des-sicated prior to development.
The cocoon surface was papyrus- 1 ike , without much loose internal silken mesh. The pupae ranged 5-4 to 5.6 mm in length. The anal legs were short, the free portion only 0.22-0.23 mm long, appressed to abdomen, with 16-20 setae situated broadly over the distal end.
Ethmia brevistriga ardicola powell
Ethmia brevistriga ardicola Powell, 1971, U. Calif. Publ. Ent., in press.
This race occurs at inland stations, mostly in the mountains marginal to the deserts. From the following fragmentary data and larval morphology, ardicola appears to have essentially the same biological characteristics as the nominate subspecies.
Study a reas . - 1) Hills two miles northeast of Lakeside, San Diego Co.; adults taken in flight without definite plant association, March 13, 1963 (J.A. Chemsak and J. Powell); 5 males, 1 female retained alive (63C2). 2) Pinyon Flat, 16 road miles southwest of Palm Desert, Riverside Co.; adults abundant at flowers of Cryptantha ?circumcissa and flying in association with Vhacelia distans subsp. australis April 7, 1963 (R.L. Langston, C.A. Toschi and J. Powell); 3 females retained alive (63D6); April 12, 19 6 3 , ^ males 5 fe-
Biological studies on Ethmia
21
males retained alive (6 3 D17) ; young larvae on P. distans var. australis, April 13, 1963 (63D20).
Adult behav i or . - This subspecies has about the same seasonal flight period as its coastal counterpart, despite the higher elevation of the inland sites (up to 5000 ft.). Moths of 6 3 C 2 were caged in a gallon breeding jar in the field with a bouquet of Cryptantha and kept under variable conditions until the fourth day. They did not begin activity until about 12:20-1:00 P.M. with the room temperature at about 18° C, even though an Ethmia minuta male in the same jar had been active for two hours. As with b. brevistriga, the greatest activity seemed to be about 4:00-4:30 P.M. The last individual ceased activity and entered the quiescent posture at 5 "• 4 0 on one afternoon, but several were active until 6:10 (dusk) on another; and moths were observed with the antennae in active position as late as 7:00 P.M. on the tenth day after collection.
Males lived 8-13 days and the female 13 days, but only 2 eggs were deposited, those on the glass side of the container. Presumably absence of Phacelia resulted in failure to initiate oviposi tion. Moths of 6 3 D17 were caged in an 85 x 100 mm jar with a bouquet of Phaoelia and Cryptantha but became water soaked in transit in an icebox from the field laboratory April 14; several recovered and two females lived until the sixth day following collection. Eggs were deposited April 14-17 on both upper and lower surfaces of Phaoelia leaves, not on buds, and on Cryptantha foliage, dry Cryptantha flowers, and on a dead Ethmia male.
The three 63D6 females deposited 1, 6, and 10 eggs in their individual, dry vials during the 2-3 days they lived.
Egg. - Eggs deposited in dry vials were evenly oval,
tapering slightly towards both ends, not as rectangulate as
in related species. The width and length ranged 0.33 x 0.63 to 0.36 x O.63 mm.
Eggs of 6 3 D 6 were stored in dry vials in warm conditions of a field laboratory and hatched in 8 to 9 days; those of 63D17 were stored under moist conditions and variable, cooler temperatures (including one to two days in a field icebox) and hatched in 8 to 13 days.
La rva . - First instar larvae hatching from eggs on the plant material, Phacelia distans subsp. australis and Cryptantha ciroumoissa were left in situ in the inflorescences, Most established feeding sites successfully on Phacelia buds, although leaf material was eaten by two individuals. None fed on the Cryptantha. Those from dry vials were placed on flowers of Phaoelia, and the flower parts served as food throughout their growth.
The second instar was reached by about the sixth day by most larvae; thereafter developmental rates varied, owing
22
albitogata
to variation in condition of the plant material.
The Phacelia stems in one of two 63D17 lots began to rot a week after the larvae hatched, and these larvae were transferred to fresh, although mature, Phacelia distans from Stanislaus County. They continued development, using mature flowers; both the flower parts and developing ovules were eaten. One larva reached the final instar by the 30th day.
A second lot was retained on the original Phacelia material from Riverside County, which remained in good condition for about 27 days after the larvae hatched. However, all flower parts were eaten by this time. Larvae fed entirely on the half of the flowers towards the center of the spike, or by cutting a hole through this side and eating the center portions out, taking whole developing seed or only their inner half. By the 33rd day the plant had dried excepting the stems, and larvae starved in the final three instars.
Laboratory reared larvae averaged somewhat smaller and were considerably paler than b. brevistriga.
First instar: Length 1.3-1.4 mm, HC^ 0.19-0.20 mm, almost colorless except ocellar area black.
Second instar: None preserved; HC_ 0.27-0.36 mm [3], pale brownish.
Third instar: Length 3-6 mm [1]; HC_ 0..46-0.49 mm, dark orange-brown; ThSh pale tan; integument, setae and crotchets unpigmented.
Fourth instar: Length 6.4 mm [1]; HC_ 0 .63-0 . 68-mm [4], orange-brown, mottled; ThSh orange-brown; integument, setae and crotchets unpigmented; AbdCr 10-11; AnCr 10.
Fifth instar [2]: Length 7.5-8.0 mm; HC_ 0.79-0.85 mm, orange, mottled; ThSh orange-brown; integument pattern similar to b. brevistriga but much paler and reduced; D_ whitish (not as distinctly white); DL_ dark pinkish or rosaceous; setae and crotchets unpigmented; AbdCr l4-l6; AnCr l4-l6.
ETHMIA ALBITOGATA WALSINGHAM
Ethmia albitogata Walsingham, 1907, Proc . U. S. Natl. Mus., 33:109.
This species is known from only a few localities in central California. It is closely related to E. ylagioboth-rae , and it was not until differences in hostplants and larvae were discovered that distinguishing morphological characters in the adults of the two species were recognized.
S tu dy a reas . - l) San Bruno Mountains, San Mateo, Co.;
Biological studies on Ethmia
23
adults common, Feb. 28 - March 1, 1 963 (CD. MacNeill and J. Powell); 5 males, 2 females retained alive (63 B 9) ; larvae on Amsinckia lunaris, May 3, 1963 (6 3 E1 ) - 2) Pt. Reyes, Marin Co.; larvae on Amsinckia spectabilis , April 31, 1967 (G.A. Gorelick) (67D149). 3) Arroyo Mocho, 15 miles southeast of Livermore, Alameda Co.; adults common, Feb. 22-24, 1 968 (C. D. MacNeill and J. Powell); 5 males, k females retained alive (68B178) ; negative results checking Amsinckia and Plagiobothrys, April 27, 1969; adults sparse, Feb. 21, 1970.
Adult behav i o r . - The moths fly in early spring, late January to early March. Presumably germination of the host plant has begun, but I have been unable to locate young Am-sinckia when the moths are flying. Adults (63B9) were caged with a bouquet of Phacelia californica, a suspect host; wh f 1 e 1968 adults were provided with young Plagiobothrys no-thofulvus, owing to a misidentification of the moth. The correct foodplant was never offered as an oviposition substrate and stimulus.
The moths exhibited a definite diurnal activity rhythm, but neither mating nor oviposition was observed. Individuals from the San Bruno Mountains commenced activity earlier, beginning to abandon the quiescent posture by about 9:30 A.M., three hours after daybreak, with the outside temperature at 9-11° C. During the following two hours all adults engaged in some movement. One female was observed to take water in this matinal "pre-activity" period. Continuous activity, with moths mostly crawling at the side of the jar towards the sunlight, took place between 12:00 and 4:00 P.M. By 4:30 some moths ceased movement, and by 5:30, with the last rays of sunlight on the jar, most individuals had assumed the quiescent posture. Adults from Arroyo Mocho, by contrast remained inactive until 10:30-11:30 A.M., even when the container was transported by car 15 miles to Berkeley. However, they remained active later, till 6:00-7:00 P.M., through the dusk period. Outside air temperatures were warmer during the 1968 observations, ranging to 24° C maximum compared to 15-17° in 19 63- Moths in both groups generally displayed a longer activity period than some of the other diurnal Ethmia, and they became active quickly if exposed to d i rect light at night.
Males lived 2-6 days, females 6-9 days, following col-1ect ion in the field.
In 1963 no eggs were deposited by captive albitogata-Presumably the Vhacelia did not provide adequate stimulus, since cage conditions were comparable to those extant during successful oviposition by other diurnal Ethmia. The 1968 females laid only 35 eggs; again absence of Amsinckia probably adversely affected oviposition behavior. Of the total, 28 eggs were placed on the helical, ribbed portion of a horizontal, screw-cap vial which held a moisture wick and Plagiobothrys bouquet. The remaining eggs were deposited on Plagiobothrys leaves (5 upperside, 2 underside).
2k
albitogata
Egg . - The eggs did not differ superficially from those of plagiobothrae. No measurements or photographs were executed. Incubation required 11-11.5 days.
Larva. - First instar larvae were placed on Plagio-thrys nothofulvus from Arroyo Mocho. Uprooted young plants nad been placed in water vials 12 days previously, and after initial die back of lateral leaves, survived well for the duration of the experiment and were sending up floral sta.lks by the time of larval hatch. Most larvae did not establish on this host. It appeared that those situated on new terminal leaves were unable to penetrate the thick pubescence; when transferred to the undersides of basal green leaves, where pubescence was less dense, most still did not feed successfully. Two individuals accepted the Plagiobothrys and fed about 7-9 days, reaching the second and third instar. Feeding occurred in the form of small skeletonized areas, with a thin silk envelope between the new leaves of the terminal growth. Although the plants remained in good condition more than three weeks after transferral to the water vials, no flowers had begun to open by the time the larvae succumbed in what appeared to be starved condition. The unavailability of flower parts rather than the wrong host genus may have been the critical factor in the failure of the 1 a rvae to ma tu re.
At San Bruno Mountains in 1963 close association of adult flight with several clumps of poison oak (Rhus diver-siloba) on rocky outcroppings, enabled discovery of larvae on Amsinckia lunavis there in early May. At this time, about 60 days after the height of observed adult activity, the plants were in full bloom, and larvae of the final three in-stars were present. There was variation between Amsinckia colonies from 75% penultimate and none full grown to $0% mature final instar and the remainder young final instar.
All larvae were found inside inconspicuous shelters formed in the flower spikes, similar to those of E. bvevi-striga. Larvae moved along the upper side of the scorpiod spike, webbing the flower parts together above the larval galleries. Feeding took place on the whole inner side of the flowers. Developing ovules and ovaries of unopened flowers were consumed, and even sepals were eaten by larger larvae. Portions of the flowers on the outer half, visible from the exterior of the inflorescence, were untouched. Petals were mostly above the area of feeding and remained intact, without discoloration or wilting. Some feeding occurred on the inflorescence stem; in one instance it was cut entirely th rough.
Shelters were not evident from the exterior, but affected inflorescences could be detected by frass clinging to the older, unoccupied portion of the spike where elongation of the stem caused separation of the partially eaten flowers, exposing silk. Frass apparently was entirely retained within active parts of the shelter, not visible from the exterior.
Biological studies on Ethmia
25
Larvae were placed in plastic sandwich boxes with small bouquets of Amsinokia. However, the viscid plant did not keep well and mould developed within three days. Yucca pith was added as a pupation site, but the colonies became affected with disease and no larvae pupated.
As in plagiobothrae t head capsule measurements did not enable definition of all instars (fig. 2). In both species either the second instar head capsules were not recovered or a greater relative size increment occurred between the first and second than in other Ethmia, Moreover, these two species exhibited two color phases in the final instar, a characteristic not observed in related species. Head capsule measurements showed only a very slightly larger average in the paler of the two phases.
First instar: (None preserved in healthy condition) HC 0.18-0.22 mm, dark brown; integument, including pinacula, unpigmented.
Second ins tar(1): [1] (Not preserved in distended condition) HC_ 0.33 mm; dark brown; integument unpigmented, Pin slightly darker; AbdCr 9-10; AnCr 9.
Third instar (?): [1] (Not preserved in distended condition) HC_ 0.50 mm; brown, unmottled; ThSh brown laterally, unpigmented mesally; D whitish, DL_ brownish gray, L_ unpigmented, LV pale grayish, Pin dark, not defined by pale areas; AbdCr 9-10; AnCr 8.
Penultimate instar: [4] Length 7.5-7.8 mm; HC 0.57-0.60 mm, dark brown, paler above labrum, not mottled; D scarcely distinguishable, whitish, E^L pale grayish (not distinct as in fourth instar plagiobothrae) , L^ unpigmented; AbdCr 6-9 (usually 8-9); AnCr 6-7.
Final instar: Length 10.2-13.0 mm (rarely, teneral?, 7.7 mm with integumental pigment reduced); HC_ 0.83-0.96 mm, strongly mottled; similar to plagiobothrae but paler, with the two color forms not as distinguished: (a) (HC_ avg. 0.88 mm) D pale without yellow-orange spots, DL_ well defined, dark to pale gray; (b) '(HC avg. 0.90 mm) D pale with segmental yellow-orange spots, DL_ and LV pale gray; Pin small, well defined, dark; AbdCr 10-20 (usually 12-l677~~AnCr 12-16.
Ethmia plagiobothrae Powell
Ethmia plagiobothrae Powell, 1971, U. Calif. Publ. Ent.; in press.
Although discovered only about ten years ago, this species has been collected many times. The larvae are often encountered in large numbers, but in the laboratory they are extremely susceptible to disease. Those which pupate frequently do not metamorphose. Only a few adults have been
26
plagiobothrae
taken in the field. Ethmia plagiobothrae is closely allied to albitogata, but the two exhibit marked biological differences .
Study a reas . - 1) Cool, El Dorado Co.; larvae abundant on Plagiobothrys nothofulvus, April 24, 1961 (C.D. MacNeill and J. Powell) (61D4, 61D5); 1 male, 1 female, March 21, 1962, female retained alive (62C2); investigated for adults, March 29, 1964 and March 23, 1965, negative results. 2) Six miles west of Whiskeytown, Shasta Co.; larvae on Plagiobothrys probably nothofulvus, May 10, 1961 (R.L. Langston and J. Powell) (61E10). 3) Eight miles south of Leesville, Colusa Co.; larvae on P. nothofulvus April 12, 1962 (j.A. Chemsak and J. Powell (62D5); investigated for adults, March 8, 1963, negative. 4) Elk Mountain, 2800-3000 feet, 11-12 miles north of Upper Lake, Lake Co.; 3 females flying in association with, 1 egg, 2 young larvae on P. nothofulvus, April 4, 1962 (62D12); investigated for adults, April 9, 1964, negative (penultimate instar larvae on P. nothofulvus at 2200 feet, one mile south on the same road); adults sparse, March 18, 196 5 (R.L. Langston and J. Powell). 5) Ten miles south of Creston, San Luis Obispo Co.; 3 larvae on P. nothofulvus, April 30, 1962. 6) Arroyo Mocho, 18 miles south of Livermore, Alameda Co.; larvae on P„ nothofulvus^ April 30, 1963; investigated for adults, February 23, 1964, March 14, 1965, Feb. 24, 1968, March 4, I969, Feb. 21, 1970, negative. 7) San Antonio Valley Ranger Station, Santa Clara Co.; mature larvae on P. nothofulvus, April 30, 1963; investigated for adults, Feb. 9, 1964, negative; 3 young larvae on P. nothofulvus, March 14, 1965; 'investigated Feb. 24, 1968, negative; 1 male, 1 female, March 4, 1969 (P.A. Opler and J. Powell); larvae common on P. nothofulvus, April 27, 1969 (69D58). 8) One mile north of Posey, Tulare Co; larvae common on P. nothofulvus. May 14, 1963 (C.A. Toschi and J. Powell) (63E2) . 9) Three miles north of Havilah, Kern Co.; 4 larvae on P. tenellus , May 15, 1963 (63 E10) . 10) Fifteen miles southwest of Havilah, Kern Co.; larvae on P. nothofulvus, May 15, 1963. 11) Havilah, Kern Co.; larvae common on P. nothofulvus, April 28, 1964 (C.A. Toschi and J. Powell) (64D10). 12) One mile east of Woody, Kern Co.; larvae on Plagiobothrys , April 25, 1964 (C.A. Toschi), May 3, 1964 (64D16). 13) Three miles northwest of Mariposa, Mariposa Co.; 3 young larvae on Plagiobothrys , March 25, 1965.
Adu1 t behav i or. - This species has a single annual flight period, in early spring. The few field collections indicate the moths fly in March and early April, ahead of or at about the time the blossom period of the host begins. The development of Plagiobothrys is highly variable from one season to another at a given locality, possibly correlated with early spring rainfall, and occurrence of young larvae in mid March, 1965, suggests that the moths are sometimes flying by mid February.
Only one female was observed in captivity (62C2). This field collected individual was caged in a one-gallon
Biological studies onfftbia
27
jar with a flat of planted herbs from Cool., and a bouquet of Phacelia californica from San Mateo County. The female showed the same activity periods and quiescent posture at night as described above for E. albitogata. On one occasion, the female did not move when lights were intermittently on from dusk until 8:00 A.M. In this instance she began activity about 10:30 A.M.
Oviposition behavior, with the abdomen distended and curled towards the leaf substrate, was observed at 12:15, 2:00 and 4 :55 P.M. one day, and deposition of eggs was witnessed at 2:30 on another afternoon. On one occasion two eggs were deposited in rapid succession, (a few seconds interval) without apparent probing of the ovipositor, followed by a third egg nearby a few minutes later. A total of 62 eggs was recorded. About two-thirds (44) were deposited on the Phacelia (figs. 24-25) and 5 more on grass blades and the glass side of the container adjacent to the Phacelia. The remainder were located on what was presumed to be basal rosettes of young Plagiobothrys. All but one of the latter group and 90% of those on the Phacelia were placed on the undersides of the leaves, which were more hirsute in both cases .
The moth lived nine days after its capture, but probably no oviposition took place after the fourth or fifth day.
Egg. - (Figs. 24-25) The eggs were more variable in shape than most other Ethmia studied, ranging in outline from rectangular-oval to ovoid, tapering at both ends; width and length varied accordingly, from 0.22 x 0.47 mm to 0.28 x 0.42 mm.
Development at laboratory temperature required 10-11 days, hatching April 2-4, 11 to 13 days after the female was first caged. Some of the eggs were stored in a refrigerator for 72 hours, and emergence of these was delayed about 3 days beyond the last of the non-refrigerated ones.
Emergence frequently took place off center from the mi-cropyle, by means of an irregular slot contrasted to the more or less evenly oval hole in the middle of the micropy-lar end, which is usually cut by larvae of other Ethmia*
Larva. - Newly hatched larvae were placed on Phacelia califovnica9 but none successfully established themselves. A few small spots of skeletonizing represented the only feeding and none of these larvae reached the second instar .
Two young larvae were collected at Elk Mtn., in the basal rosettes of Plagiobothrys , but their shelter and feeding were not observed. When preserved, they were in the second and third instar.
Larvae of at least the final tw.o instars fed entirely exposed, on the flowering stalks of Plagiobothrys. No visible silk nor other shelter was employed. Larvae could be
28
plagiobothrae
found curled around the uppermost flower, feeding on the in-f1o res cences.
Frass was flipped free of the flower parts, appearing on the sides of the container.
In the following larval diagnosis, specimens from Cool and Havilah are mixed in the final two instars. Those from Havilah average smaller, but the ranges of variation are similar.
Evidently this species has five instars (fig. 1), with two well defined color phases in the final instar. It was originally assumed that two instars were involved, but head capsule measurements do not show an appreciable separation. Form (a) has dark gray, almost black Integumenta1 markings with yellowish spots in the dorsal band, while (b) has much paler gray integumental bands and conspicuous orange blotches on each segment except the prothoracic. The pale form Cb), larvae seemed bulkier and apparently were more mature, but I had no evidence that an ecdysis occurred in develop-men t of (a) to (b) .
First instarl^']: Length 1.0-1.2 mm; HC! 0.20-0.22 mm, pale orange with ocellar area black; integument and setae colorless.
Second instar\_l~] : Length 3.0 mm; HC_ 0.36 mm, dark brown; ThSh, Pin small, and setae dark, integument unpig-mented; AbdCr~p^7; AnCr 7-8.
Third instarll']: Length 3-3 mm; HC^ 0.49 mm, lighter brownish; ThSh not defined; Pin brown, as small as in 2nd instar; integument unpigmented; AbdCr 9-10; AnCr 11.
Fourth instar: Length 6.3-8.8 mm; HC 0.53-0.60 mm, dark brown, poorly defined pale area above labrum; Pin small, dark; IXL pale gray, D well defined, LV scarcely pigmented; AbdCr 9-11 (Cool) or 7-0 (Havilah); AnCr 9-11.
Fifth instar: Length, form (a) 10.0-13.0 mm, form (b) 12.9-15.8 mm; HC_ 0.75-0.85 mm (Havilah, (a) average 0.77, (b) average 0.79 mm), 0.77-0.88 mm (Cool, both forms average 0.83 mm), orange-brown, strongly mottled; ThSh darkened laterally only; Pin black; D white, well defined, each segment except prothoracic with a bright orange blotch as broad as D; DL_ gray, narrow; L pale with dull, irregular blotch above spiracle; LV pale gray, irregularly mottled; AbdCr 16-20 (usually 17-19), biordinal mesally; AnCr 19-21, biordinal.
Pupa. - Successful pupation occurred in folds of paper toweling or tissue paper, and in yucca pith. Under laboratory conditions most individuals either died as prepupae or young pupae or remained in diapause and did not emerge. On two occasions (61D 4 , 63E2) single moths emerged early the following year and twice pupae were still healthy appearing
Biological studies on Ethmia
29
during the second winter: two pupae of 61E10 in December 1962 (19 months after pupating), and one of 64D10 in February 1966 (after 21 months). The latter was placed in an outdoor cage at Berkeley through the spring, 1966, but still did not emerge. Larvae from several lots constructed cocoons in corners of salve tins, and in one case between a cotton plug and glass side of a vial. In all these cases prepupal larvae or pupae became dessicated and collapsed prior to development.
Full grown larvae from San Antonio Valley (69D58) were placed in 35 mm square pill boxes or small salve tins, two or three individuals per container, with a block of yucca cortex in each. After storage at laboratory temperature for 10 weeks they were transferred to the outdoor shed in July. Successful emergence occurred by late February in over 60% of the individuals, suggesting that temperature and moisture rather than photoperiod are stimuli which are important to development during the pupal stage. Cocoons were formed in cracks in the yucca or between the yucca and paper liner.
Pupae from Cool ranged 5-0-5.6 mm in length. The anal legs were dorsoventra 1 1 y flattened more than in other Ethmia studied. In addition they showed a definite tendency for greater lateral expansion distal 1y (appearing boot-shaped in outline rather than evenly expanded laterad and mesad). The free portion was about 0.24-0.27 mm long, with a lateral projection of 0.09 mm. The legs had 32-36 (rarely 38) hooked setae which are about 0.05 nfm in length. The setae of the cremaster area were 0.12 mm long and relatively strong, remaining intact during emergence of the moth.
Natural enemi es, - About h0% of the groups of larvae in various types of containers became diseased and nearly all larvae in these lots succumbed prior to pupation. Representatives from two affected collections (6 4 D10 , 6 4 D16) were submitted to the Division of Invertebrate Pathology at the University of California, Berkeley. G.M. Thomas responded (in litt.), indicating that media inoculated directly from titurated specimens produced pure cultures of a Pseudo-monas sp. and that observations indicated this bacterium was the cause of the disease.
It is assumed that the epidemics were brought on by conditions in rearing, since similarly affected larvae were not commonly seen in the field, and in at least two cases (61D 4, 64 D10) containers with few larvae did not show the symptoms while those with larger groups did. However, the high incidence of these epidemics and the fact that such symptoms occurred only in this species, albitogata, and oharybdis , indicate that the body flora of these larvae differs from that of most Ethmia, causing them to be more subject to disease. This may help account for the fact that larvae of these three species are more easily found in high numerical density in the field than the adults, whereas the reverse is true with other Ethmia I have studied.
30
minuta
Ethmia minuta Powell
Ethmia minuta Powell, 1971, U. Calif. Publ. Ent., in press.
This species was collected in southern California as early as 1916, but probably it was not recognized as an Ethmia owing to the small size. The elongated, strongly scler-otized ovipositor and smooth egg are features unique to this species among known New World Ethmia.
S tudy a reas . - 1 ) Hills 2 miles northeast of Lakeside, San Diego Co.; adults at midday flying and on flowers of Cryptantha intermedia, March 30, 1961 and March 13, 1963. 2) Two miles northeast of Moreno, Riverside Co.; males flying in midafternoon, April 5, 1963 (C.A. Toschi and J. Powell); both sexes flying in association with Cryptantha intermedia, April 12, 2:00-4:00 P.M., h males, h females were retained alive (6 3 D18) .
AduIt behavior. - Ethmia minuta has a single, early spring flight, from mid March to late April. The moths are diurnal. The four pairs from Moreno were caged in an 85 x 100 mm jar with a bouquet of Cryptantha April 13-1^ under field laboratory conditions. About 20 eggs were deposited during this time, but no observations on behavior were made. On the following day the moths became water soaked during transport from the field in an ice box. Three females partially or fully recovered, and one lived until April 17. It was observed on the Cryptantha once, but no oviposition occurred after April \h.
Eggs on April 13 were all deposited between bases of flower buds (figs. 18-20). These were located only in inflorescences with partially developed flowers. Those with larger green seed and no blossoms left were not used for oviposition. Evidently the elongated ovipositor of E, minuta is an adaptation for use of the densely bristled inflorescences of Cryptantha intermedia.
Egg. - (Figs. 18-20) In contrast to all other species for which eggs were studied, those of minuta had a smooth chorion, without visible network of structural ridges under 5^x magnification. The shape was roughly oval, circular in cross section, measuring 0.30 x 0.^3 mm to 0.25 x 0.^7 mm; variation resulted from the situation of placement. Upon dissection of the flowers most eggs were found to be wedged between a sepal and upper portion of a carpel. Emergence of larvae invariably occurred from the inward end of the egg, adjacent to the carpel. Hatching occurred April 22 (± 10 days incubation).
La rvae. - Some of the buds on which the eggs were deposited had dried by the time the larvae began emerging, and they were placed on the exterior of green buds. They seemed unable to crawl on or penetrate the densely bristled vesti-ture, and several died. None attempted to feed on stems;
Biological studies on Ethmia
31
no leaves were available.
By opening buds slightly with forceps and inserting two day old larvae, I was able to provide conditions which enabled feeding. Whether the few larvae which successfully established included any of these, or were only those which entered directly from the eggs, was not determined. Feeding by first instar larvae took place at the sides of developing ovules. There was no feeding on petals or sepals > and larvae placed in buds which were too young to have developing ovules did not feed. Most died without establishing successfully, even after some feeding.
Those surviving hollowed out developing ovaries. Second instar larvae were transferred on the fourth day from the drying buds to buds which had been refrigerated two weeks. Again larvae had to be placed into forced open buds and not all succeeded in feeding.
On the twelfth day two third instar larvae were placed on new Cryptantha from the refrigerator (originally taken with the moths 21 days earlier). These larvae experienced considerable difficulty and were unable to penetrate the bristled buds after one hour. The two were then placed on flowers which I broke open, but they were still unable to establish easily. After another hour one larva succeeded in beginning feeding on the inner side of the ovary wall. This larva lived until the 17th day after hatching. By this time, however, the 26 day old Cryptantha failed to take up water when removed from the refrigerator and no additional food-plant was provided.
First instar: Length 1.0-1.25 mm, HC: 0.16-0.17 mm, pale tan, almost colorless, ocellar area black; integument and setae colorless.
Second instar: None preserved; HC_ 0.27-0.29 mm [2]; integumental markings evident as pale yellow-orange or ochreous-tan blotches surrounding the DL pinacula.
Third instar[2^: Length 3-7-4.2 mm; HC 0.36-0.41 mm, pale to dark brown; DL_ mottled pale olive-brown; Pin not differentiated, setae and crotchets colorless; AbdCr ±8; AnCr ±8.
Ethmia charybdis Powell
Ethmia charybdis Powell, 1971, U. Calif. Publ. Ent.; in press.
This bizarre species is known from only three localities, having been discovered when we reared a male from larvae collected in 19 67- The moth is unique among all Ethmia by possession of extremely elongate and peculiarly thin legs, as well as by markedly reduced mouthparts. Primarily on the basis of male genital characters charybdis had been placed
32
charybdis
as a monobasic species group related to the diurnal group. However, with the discovery, in 1970, of the female which is brachypterous, reevaluation of the species' assignment to Ethmia is anticipated.
According to the geographical distributions of the hostplant and of other insects which occur at the type locality, we expected colonies of charybdis along the western edge of the San Joaquin Valley and in the Mojave Desert. This has proven to be the case, with collection of larvae in the Mojave in 1970 and recognition of apparently conspecific larvae in the U.S. National Museum collection which had been taken in the southeast corner of San Luis Obispo County , in April 1956, "sweeping wheat and various flowers", by G. Bee-vor of the California State Department of Agriculture. Examination of Amsinckia tessellata in a similar habitat to the type locality, at Jocalitos Canyon near Coalinga, Fresno County, in early February and late March proved negative.
S tudy a rea s. - 1) Big Panoche Creek, near Fresno-San Benito County line; larvae on Amsinckia tessellata* April 20-21, 1967 (J. Powell and P.A. Rude) (67D87); 1 young larva on Amsinckia, March, 1 968; negative results checking Amsinckia intermedia and A, gloriosa, March 5, 1969, and A. tessellata, April 23, 19&9, an<^ with Amsinckia not yet germinated, Feb. 5, 1970. 2) Ryan Mountain, Joshua Tree National Monument; larvae on Amsinckia intermedia* March 31, 1970 (R.E. Dietz and J. Powell) (70C13).
Adu1t behav ior. - Only two adults, from Ryan Mountain, have been observed alive, serving as indicators of the seasonal and diel activity periods. Emergence occurred at the end of November and beginning of December, after pupal aestivation in closed containers which were housed under laboratory conditions through the summer and in a modified outdoor situation during fall. Field surveys have not been carried out during the fall months, but the normal flight period is presumed to be late fall or winter, in part through comparison with the life cycle of E. timberlakei , discussed below, and in part owing to the brachypterous condition of the female in charybdis , a characteristic of certain winter mot hs in othe r taxa.
As is true in other fall flying Ethmia* adults of charybdis possess large eyes and nocturnal habits despite the fact that activity, in November in desert habitats, must take place in cold, temperatures. Moreover, there was an indication in laboratory charybdis that activity is restricted to early morning hours rather than at dusk or early darkness, when it was warmer. No crepuscular movement occurred, and on several evenings activity by one or both individuals did
1 Probably in the vicinity of Cuyama according to M.E. Gardner, Bureau of Entomology, Sacramento, California.
Biological studies on Ethmia
33
not begin prior to 4-6 hours after nightfall. In every observed nocturnal cycle both moths moved after 11:00 P.M. This behavior may have been artificially induced, because the moths were housed at about 16-18° C during daylight and early evening, and in temperatures declining to about 12-14° C between 11:00 P.M. and 8:00 A.M. It may be that optimal temperatures for oharybdis are well below 16-18°, and in the field that might occur in early evening. It is not unreasonable to suppose that this species is active at colder temperatures than any other known Ethmia- By comparison, the geometrid winter moth, Operophtera bvumata (L .) , in which the female is brachypterous, has been observed to mate and oviposit at temperatures just under 0° C (Cuming, 1961), whereas most other Geometridae, even species which fly only in early spring, are rarely active below a temperature range around 4-5° C, and not at all below 2-3° C according to light attraction records (Powell, 19 6 2) .
As in the case of timberlakei , Ethmia oharybdis was able to survive without water. The proboscis is short and may not be functional. No moisture was provided during the first 7-9 days the male was alive or the first 3_4 days following emergence of the female. Whereas a shorter period would have been lethal to most Ethmia, there was no evidence of weakening of the oharybdis adults, and mating took place during this time. Ultimately the male was killed when 10 or 11 days old, while the female, after an oviposition period during which she was provided with water, died 6-7 days after erne rgen ce.
Mating occurred during the second or third night following emergence of the female, when the male was 6-8 days old. Copulation was initiated after 11:30 P.M., on an evening when both individuals had been active between 6:30 and 11:30. The pair remained in coition approximately 22-26 hours, showing no signs of activity during this time (even when exposed to electronic flash and direct sunlight for several minutes during photography). Separation occurred, with both male and female moving away, between 4:00 A.M. and 8:00 A.M.
Oviposition behavior was not observed, but it occurred between 12-72 hours after completion of mating and could have begun immediately in the matinal period following mating. Although no protein was provided, the single female deposited 75 eggs, the highest total I recorded for an individual Ethmia. The eggs were placed in depressions and holes in yucca pith and under and between layers of tissue paper. The female selected cracks and open beetle galleries in the yucca piece for 11 eggs, which were recessed up to 0.6 mm below the surface. Most of the oviposition (58 eggs) occurred in creases, between layers, and onto the underside of tissue paper liners of the original larval containers and fresh paper provided in the breeding cage. Three eggs were nested adjacent to mouldy frass on the tissue, suggesting that larval evidences on old foodplant may
3h
oharybdis
elicit oviposition stimulus. Dry flower and leaf fragments of Amsinckia tessellata from a herbarium sheet were provided but were not selected by the female.
E gg. - The eggs were characteristic of other Ethmia in shape and chorion sculpture but were smaller than those of other nocturnal species with forewing length comparable to that of male charybdis. Eggs ranged 0.37 x 0.62 mm to 0.30 x 0.67 mm in outline, about the size of those of diurnal species, which the female approximates in body size. Stored at laboratory temperatures, all but a few apparently infertile ones turned yellowish within 3 days, to a peach color by 7"9 days, and later gradually reddish. They showed no signs of maturation by the 15th day, suggesting diapause, but they did not rapidly change to a tomato red color characteristic of eggs in diapause in Ethmia timbevlakei and in tortricine moths (Powell, 196*0. However, color transition Tn timbevlakei was not observed and may be a gradual, slower process as in the present species.
Larva . - Younger ins tars were not observed; individuals thought to be antepenultimate and penultimate were taken by net sweeping. Mature larvae lived exposed on the inflorescences, usually perching on one side, below the highest part of the plant, without any visible webbing. In the laboratory those of the last two instars housed in 32 x 90 mm plastic vials proved to be susceptible to disease epidemics, even though individuals were separated, a few in each container. Others placed in 25 x 75 mm salve tins were less susceptible, and several matured successfully. Shelters were spun among flowers, but these may have been constructed only in preparation for pupation. Feeding probably occurs primarily on developing seed and flower parts under natural conditions.
At maturity larvae spun opaque cocoons in corners of the rearing containers or in foliage (67D87). No soft, woody substrates were provided. The 1970 larvae were offered yucca blocks bearing galleries of cossonid beetles, but the three larvae which successfully completed cocoons all selected folds of tissue paper.
Penultimate instar (?) [2]: Length 9-7-10.0 mm. HC O.58-0.71 mm; orange, indistinctly mottled with brownish; ThSh brownish, fairly well defined; integument color as in final instar, paler than most but not all individuals; AbdCr 7-10; AnCr 9-15.
Final instar: (Fig. 7) Length 10.0-16.0 mm. HC_ 0.85-0.97 mm; orange, distinctly mottled with brown; ThSh not well defined, sclerotized areas restricted to posterior margin; integument pale to distinctly colored, D white with a median rust-orange streak (sometimes reduced to a trace), DL_ fairly uniform dark to pale gray, mottled, defining distinct white circles around pinacula; L white, well defined, with variable elongate blotch of pale to bright rust-orange, LV as in DL,
Biological studies on Ethmia
35
usually slightly paler; Pin large, black, distinct; AbdCr 15-21; AnCr 21-22. Segment A9 with 0 or 1 very small secondary seta at LV, anal leg with small patch of usually 3 tiny secondary setae.
Pupa . - Pupation occurred in various cocoon situations, but lack of suitable substrates may have ultimately resulted in dessication of several prior to development. The only successful emergences occurred from a cocoon tightly spun in old foliage and flower parts in 1967 and in tight folds of tissue paper in 1970.
Preserved pupae measured 6.0-6.8 mm in length, were smooth, pale orange, without specialized spiracle structures. The anal legs were rather short with slight to no lateral extension distal 1 y , with 20-22 anchoring setae. The frail cremaster homologue setae were located on a roughened, but not depressed area.
Ethmia albistrigella (Walsingham)
Pseoadia albistrigella Walsingham, 1880, Proc. Zool. Soc. Lond., 1880:89.
Described from the Siskiyou Mountains on the northern border of California, albistrigella is widespread in western North America, occupying more boreal regions than the closely related nadia> discussed below. Both have small eyes, but according to phenetic assessment are more closely related to members of the semilugens group which are nocturnal, than they are to the foregoing diurnal species (Powell, 1971). It is possible that small eyes and diurnal habits in albistrigella are a secondary development as a result of adaptation to high elevations where temperatures early in the season deter night time activity.
S tudy a reas . - 1) Chipmunk Flat, 3 miles west of Sonora Pass , 8800 feet, Tuolumne Co.; adults associated with Pha-celia ramosissima, June 25, 1962 (C.D. MacNeill and J. Powell) 2 males, 3 females retained alive (62F1 1) ; and July 1, 1962, I male, 1 female retained alive (62G4) . 2) Donner Pass, 7300 feet, Nevada Co.; 1 male, 1 female flying near P. ramosissima, July k, 1962 (C.A. Toschi and J. Powell); larvae on P. ramosissima. August 3, 1962 (62H3).
Adult behavior. - Ethmia albistrigella has a single annual generation, flying early in the season, in California from mid June to mid July, after the snow in the vicinity has receded to patches and the Phaoelia has not yet begun to bloom. Adults were apparently actively flying between 1:00 and 3:00 P.M., and I have seen no record of collection of this species at light. In the breeding jar, adults were caged with a bouquet of Phaoelia from the collection site. They did not show a definite activity period, but laboratory conditions probably differed more (especially warmer in late afternoon, night and early morning) from field conditions with this
36
albistvigella
boreal species than for any other species studied. Most albistvigella moved occasionally or were actively crawling during morning hours, as early as 8:30. Most were active, crawling towards the daylight side of the container, feeding at water, etc. between noon and 5:00 P.M. However, many instances were noted in which moths moved after dark, both with and without lights in the room. They did not seem to be continuously active after dusk, but they were not consistently inactive as in the cases of the diurnal species discussed above.
One mating pair was observed at 8:00 P.M., just prior to sunset, having coupled after 6:30 P.M. Separation occurred in the dark, between 9:15 and 11:00 P.M.
Oviposition was not witnessed, but took place between 1:00 and 2:30 P.M., and at least once between 8:30 P.M. Cdusk) and 8:30 A.M., after six days confinement of the female. Eggs were placed only on the Phaoelia leaves, excepting one or two placed on the glass adjacent to the Phaoelia. About 70 eggs were deposited by 3 females, almost exclusively on the undersides of the leaves; 2 each were placed on uppersides of leaves and on stems.
Egg. - The shape of eggs was more variable than any other species studied, ranging from oval to kidney shaped or constricted towards one end. The width and length ranged 0.38 x 0.8^ to O.hk x 0.9^ mm. Hatching occurred after about 10 days at laboratory temperatures.
Larva. - First instar larvae emerged July 7 and were placed on an immature flowering spike of Phaoelia vamosis-sima which had been taken at Chipmunk Flat six days earlier and kept in water. Within two hours, several had begun skeletonizing leaves. Usually the underside of the leaf was selected. Later emerging larvae were placed in plastic vials with leaves and began feeding successfully. By the fourth day successfully established larvae were still in the first instar, located either on the underside or in curled portions on the upperside and had skeletonized several small spots.
After the 9th day larvae were supplied with leaves from a greenhouse Fhacelia vamosissima transplanted from Chipmunk Flat on June 2h. The cut pieces were accepted but turned black after a day or two. A leaf of Phaoelia distans from San Francisco was supplied to second instar, 11 day larvae, but little attempt was made to feed on it. Thereafter, the greenhouse P. vamosissima was used.
By the 161 h day all larvae were third instar. Two days later some individuals had reached the fourth instar and were feeding on the full leaf thickness. Generally, very little silk was used in visible shelter preparation.
On the 2^th day third and fourth instar larvae were transferred to a branch of P. vamosissima in water. All be-
Biological studies on Ethmia
3
gan feeding without any apparent shelter.
The four surviving larvae reached the fourth and fifth instars by the 28th day, and Phaoelia ramosissima from Don-ner Pass was provided.
Some larvae were full grown by the 31st day, appearing blackish with a dull orange-brown dorsal median band. The final larva began its cocoon on the 39th day.
Larvae were observed in the field at Donner Pass 30 days after adults had been collected at this site. By this time the plants had reached full to late bloom in somewhat sheltered, east facing exposure. The larvae, in the third and fourth instars, lived in thin webbing shelters among the inflorescences, usually more or less on the underside of the flowering spike, rather than between the geminate flower rows. The silk was not easily visible, but presence of the larvae was evident by frass, retained by the hairy, viscid texture of P. vamosissima. Lower leaves were thoroughly investigated and neither larvae nor signs of larval feeding were found.
Two larvae reached the final instar one day after this field collection, and the first larvae spun cocoons on the 12th day following collection (42 days after adults were ob se rved at the site).
There appeared to be five instars, based on unsexed head capsule measurement (fig. 5). However the size range in later instars suggests a possible sixth instar in occasional individuals.
Second instar: (None preserved) HC_ [5] 0.36-0.40 mm, pale orange with slightly darker mottling.
Third instar: Length 5.0-9-9 mm; HC_ 0.55-0.78 mm, orange-brown to dark brown, mottled paler; ThSh pale orange-brown; Pin dark but somewhat diffuse; D whitish, not well defined; DL scarcely evident, ochreous yellow; AbdCr 7-8; AnCr 6-9 lusually 8-9).
Fourth instar: Length 10.4-12.0 mm; HC: 0.86-0.96 mm, white anteriorly with dark brown posterior markings; ThSh mottled laterally only; Pindark, small; D unpigmented, not well defined; DL pale ochreous or olive-green with whitish encircling pinacula; AbdCr 9; AnCr 10.
Fifth instar [3]: Length 12.2-14.2 mm; HC 1.22-1.32 mm, white anteriorly with black posterior markings; ThSh mottling restricted to small areas at posterior margin; D well defined, unpigmented to dull orange-brown; DL, LV well defined, dark gray to blackish, mottled with unpigmented areas; L well defined, pale, unpigmented or tinged with orange; AbdCr 13-15; AnCr 15-17. Segment A9 with 3 tiny secondary setae just anterior of LV seta.
38
nadia
Pupa. - Full grown larvae were placed in a salve tin with pieces of dry Phaoelia stems from Donner Pass. The stems were 2-k mm in width and were hollow or had a soft, pithy context throughout. No larvae used these stems for pupation. Cocoons were spun in the upper and lower corners of the tin. Kept at room temperatures and humidity, the pupae dessicated prior to development. Cocoons were about 12 x h.5 mm, with a dense, white papery cover and little i nte rna1 silk mes h.
Pupae ranged 6.8-7.1 mm in length. The anal legs var-te d in divergence, with one individual having them nearly adjacent. The distal portion had no lateral development and bore about 18 hooked setae. The frail, posterior "cre-master" setae were all short, possibly broken, in the individuals examined. They originated from a depressed, smooth area subtending lateral humps.
Ethmia nadia Clarke
Ethmia nadia Clarke, 1950, J. Wash,. Acad. Sci., 40:l6l.
A difficult taxonomic problem exists concerning relationships of nadia and alhistrigella- The present species occupies generally warmer, drier (Upper Sonoran and Transition Zone) regions than the boreal sites (Canadian and Hud-sonian Zone) observed for alhistrigella in California. In addition, it appears that nadia is primarily crepuscular. Possibly it is not obligated to diurnal activity by low night time temperatures as is alhistrigella at higher elevation stations.
S tudy a reas . - 1) Fowler's Camp, 5 miles east of Mc-Cloud, Siskiyou Co.;l male at Coleman lantern July 7, 1957; 2 males, 1 female, net collected, apparently actively flying in late afternoon and at dusk, July 14, 1962; negative results in examination of Phacelia mutahilis, July 21, 1966. 2) Hills back of Citrus Experiment Station, University of California, Riverside, Riverside Co.; larvae on Phacelia ramosissima var. suffrutescens, May 13, 1962 (62E8). 3) Herbert Creek, 3 miles west of New Almaden, Santa Clara Co.; 1 female net collected between 1:00-2:00 P.M., April 20, 1966 (A.J. Slater and J. Powell); retained alive (66D21).
Adult behav i o r. - Although the moths have been collected in March and April in southern California and June and July in northern California, it seems likely that a single annual flight is Involved. It occurs late in the season compared to other species with small eyes, and is correlated with flight later in the day, at least into a crepuscular phase. In addition to afternoon, dusk, and evening collections listed above, single adults have been taken in the daytime: at Riverside, on flowers of Cryptantha intermedia (P.H. Timberlake); at Fairview, Tulare County, at midday, April 27, 1964 (P.A. Rude); and 9 miles south of Fairview,
Biological studies on Ethmia
39
in late afternoon, April 29, 1964 (P.A. Rude).
A reared female was observed in January 1963, over a 16 day period. No males were available. At laboratory temperatures this individual was active, crawling and feeding at damp cotton, at dusk and each evening with lights on in the room. The moth was not active in morning hours and was not observed to move much during the afternoon. No eggs were laid. When prodded during evening activity periods, the moth would feign death, dropping to the substrate on its back, with the legs tightly clasped to the body. After a few minutes activity was resumed.
The female from Santa Clara County (66D21), caged in April, 1966, was observed only on the first night. It was not active between dusk and 9:30 P.M., or between 5:00 and 5:30 A.M., resting in the quiescent posture. Retained at outdoor temperatures in a 100 x 85 mm jar with a bouquet of Phaoelia distans , (the only Phaoelia discovered at the collection site), the moth lived only five days. At least two eggs were deposited between 5:30 P.M. and dusk on the first day and ultimately 2k eggs were laid. Oviposition sites varied in these conditions (crowding and unnatural orientation of the Phaoelia branch may have been factors). Half the eggs were placed on leaves, both upper and lower surfaces, with the remainder on flower heads (M , stems (2) and the nylon screen over the jar (4).
Egg. - The eggs were nearly cylindrical, measuring 0.40 x 0.80 to 0.38 x 0.85 mm.
The eggs were placed in a refrigerator from April 25 to May 3, and were then stored at room temperature. Hatching occurred after about 17 days (including the 9 days in cold s to rage) .
La rva . - Newly hatched larvae were placed on a cut sprig of Phaoelia tanaoetifolia from the Botanical Garden in a salve tin. Two day old larvae had established mostly on spots under leaves against the salve tin surface. Feeding occurred as skeletonized spots on either upper or lower surfaces of the leaves. However, as the plant material began drying, by the fifth day, all larvae dispersed and escaped owing to a faulty container.
Field collected larvae at Riverside in the final and penultimate instar differed markedly in appearance from albistrigella, appearing olive-green with a pale dorsal band. The plants were in full bloom and larvae spun a thin web which enclosed a terminal raceme or a leaflet or two.
Penultimate instar: Length 13.0 mm [1]; HC 0.95-1.07 mm [4]; ThSh not differentiated; Pin minute; no integumental pigment; AbdCr 11-12, uniordinal; AnCr .11 .
Final instar: Length 16.5-17-5 mm; H<3 1.22-1.28 mm,
40
semilugens
orange, strongly mottled with whitish; Pin small, black; D, L fairly well defined, yellowish; DL_ pale olive-gray, mottled, with whitish encircling pinacula; AbdCr 17-19, biordin-al mesally; AnCr 17. Segment A9 with about 12 tiny, unpig-mented secondary setae in a row between LV and V setae.
Pupa. - Cocoons were spun in the leaf material and in folds of paper toweling. The outer layer was dense, whitef tough, paper-like and could be torn when dry. Inside, cocoons had an ill-defined but strong mesh surrounding the pupa, making it difficult to extract pupal shells intact. Pupae were formed before early August. Successful emergence occurred from nearly all those which had pupated, although they were stored in laboratory conditions. Emergence took place tn December and January, well ahead of that of field conditions.
One pupa measured 8.2 mm in length. The anal legs were irregularly to strongly divergent or curved, with a slight lateral development distally. About 30 setae were located in the anchoring group on each leg. The "cremaster" setae were short (possibly broken), in the individuals examined, and were borne in a shallow V-shaped, roughened depression.
Ethmia semilugens (Zeller)
Psecadia semilugens Zeller, 1872, Verh. Zool.-Bot. Ges., Wien, 22:561.
This species is widespread in arid areas from Colorado to Chihuahua and southern California (Powell, 1959, 1971). Although there had been only a single record for California, we were fortunate in discovering larvae on two species of Fhacelia at one locality at the northern end of the Panamint Valley in 1969.
Study a rea . - Darwin Wash, 1-3 miles west of Panamint Springs, Inyo Co.; larvae on Fhacelia calthifolia> May 12, 1969 (P.A. Opler) (69E65); larvae on P. calthifolia and P. crenulata, May 1A, 1969 (J • Powell and P.A. Rude) (69E78, E79).
Adu1t behav i o r. - Collection records indicate this species is facultatively double-brooded, with flight records for late February and March to September, but mostly in April and July. Records in California are for April and May, and individuals we reared either emerged in July or went into a prolonged diapause. The moths are nocturnal, judging from eye size and light attraction records. Adults were not observed in the laboratory.
Egg . - (J nknown .
La rva. - Individuals of at least four instars were found on annual plants along a rocky roadside and wash bottom, a
Biological studies on Ethmia
41
site which had been heavily eroded during the preceding winter. The caterpillars lived externally on the undersides of leaves and stems without any visible webbing. Feeding evidently occurred entirely on leaves, although both host species were in bloom at the time. In the laboratory, larvae were housed in polyethylene bags or plastic freezer dishes and continued to feed more or less exposed. Foliage of the two plants became mouldy easily. However, larvae did not seem to be susceptible to disease outbreak and provided with refrigerated leaf material, larvae matured 7-l4 days following collection.
Cocoons were formed in folds of paper toweling. No soft woody substrate was offered. Mature larvae took on a pinkish cast while wandering in search of pupation sites.
Head capsule measurements did not clearly define in-stars, and there may be six instars in this species. The following diagnosis represents a somewhat arbitrary instar division, based in part on crotchet numbers and secondary setae.
Second instar (?): [4] Length 3-5-6.0 mm; HC 0.32-0.48 mm, unicolorous dark brown; integument unpigmented, body appearing more or less uniform pale green; ThSh brown, nearly unicolorous to blotched; Pin dark, conspicuous, but relatively smaller than in later instars; AbdCr 9-13, uniordin-al, essentially a complete circle; AnCr 7-8•
Antepenultimate instar: Length 7.0-10.5 mm; HC 0.56-0.75 mm, color of HC_, ThSh, and integument as in preceding instar; AbdCr 8-15 (usually 10-13), partially biordinal; AnCr 8-12.
Venultimate instar: Length 12.0-14.5 mm; H<3 0.85-0.98 mm, whitish mottled with extensive blackish areas; integument color as in preceding instars, except D yellow, DL darker greenish, L with a yellow blotch on each segment; Pin darker, larger; AbdCr 13-16; AnCr 10-12.
Final instar: Length 15.5-23.0 mm; HC^ 1.07-1.36 mm, white with black markings posteriorly; ThSh unpigmented except two lateroposterior, variable black patches; D bright yellow, DL_ bright green with unpigmented areas around pinac-ula; L whitish with large yellow blotch on each segment; LV greenish; Pin large, black; AbdCr 15-28 (usually 20-24), biordinal; AnCr 20-24, biordinal; segment A9 with 3-6 small secondary setae between LV and V setal groups.
Pupa. - Cocoons spun in folds of paper toweling were flat, oval, with an opaque, white cover; pupation occurred within 10 days of cocoon construction. All pupae apparently entered diapause. A few emerged in early July, after 6-7 weeks at laboratory conditions. The remainder did not metamorphose; exposure to outdoor shed conditions through the following year failed to stimulate completion of development
k2
arotostaphylella
and emergence. Some appeared to remain viable after 16 months .
Pupae (figs. 8-9) ranged 8.6-9.1 mm in length and were unusually dorso-ventrally flattened. Each spiracle was followed posteriorly by a raised area which was subtended ven-trally by about 50 tiny spicules. The anal legs were moderately to strongly diverging, well separated at the base, dtstally without any enlargement. Each had 15~l6 hooked setae. Caudally h "cremaster" setae were borne on each of 2 raised areas corresponding to the anal prolegs of the larva, and these setae were stronger than on other Ethmia examined, yet still non-functional.
Ethmia arctostaphylella (Walsingham)
Pseoadia arotostaphylella Walsingham, 1880, Proc. Zool . Soc. Lond., 1880:88.
Speculation that the name arotostaphylella is a misnomer and that Eriodiotyon is the host of this species (Powell, 1959) has proven to be correct. Ethmia arotostaphylella has been found closely associated with Eriodiotyon in various parts of California on many occasions, while no evidence that Arotostaphylos is a foodplant has been forthcoming. Adults fly in late afternoon and at dusk around Eriodiotyon plants, and they can be found resting on the leaves or flushed from foliage during mid day. They have been taken on E, californicum at many stations in northern California, on E. trichocolyx var. lanatum in San Diego County, on E. orassi-folium in the Santa Rosa Mountain foothills of Riverside County, and on E. tomentosum in San Luis Obispo and San Benito Counties. The study areas cited below are only those in which early stages have been involved, among the many records for the moth's occurrence on Eriodiotyon*
S tudy a reas . - 1) Carson Ridge near Woodacre, Marin Co.; 1 female, 2 larvae, on Eriodiotyon californioum May \k , I960 (6 0 E 1 ) . 2) Hills north of Alpine Lake, Marin Co.; larvae on E. californioum, May 28, 1960 (J.M. Burns and J. Powell) (60E6); adults on E. californicumt April 17, 1961 (C.D. Mac-Neill and J. Powell), 5 males, 7 females retained alive (61 n3). 3) Three miles west of Stoneyford, Colusa Co.; young larvae on E. californicum, May 11, 1961 (61E 1 3) - M Ten miles east of Clearlake Oaks, Lake Co.; 1 mature larva on E. californicum, May 11, 1961 (61E1A). 5) Two miles east of Groveland, Tuolumne Co.; 1 larva on E. californicum, June 12, 1961. 6) Mt. Diablo, 3000 feet, Contra Costa Co.; 2 larvae on E. californicumy July 17, 1961 (61G 2) . 7) Eight miles north of Boulder Creek, Santa Cruz Co.; 1 male, 1 female, 1 cocoon on E. Qalifornicum, Aug. 11, 1962 ■ (62H6) . 8) Five miles east of Boulder Creek, Santa Cruz Co.; adults, cocoons, larvae on E. californioumt Aug. 11, 1962 (62H7).
Biological studies on Ethmia
43
Adult behavlor. - In the foothills of central California the moths fly as early as February, commonly in April and in all subsequent months until September. Adults and larvae occur together during summer, suggesting overlapping generations. At higher elevation sites spring emergence occurs in May, and only two generations may obtain.
In the field the moths become active before sundown and fly into the night, according to light attraction records. In the laboratory activity began by 6:00 P.M., prior to sunset, and was highest during the next two hours. Some individuals remained active as late as 11:00 P.M., but they moved more slowly and activity generally appeared to diminish late at night, although temperature change was not occurring.
When at rest during the daytime, both in captivity and in the field, the moths assume the characterisitic quiescent posture and often perch on the upperside of the elongate Eriodiotyon leaves, oriented with the body axis along the mid vein. The white and grey color pattern causes the moths in this position to resemble bird droppings.
Mating pairs were observed four times. One pair was swept from Eriodiotyon californioum at Mt. Tamalpais, Marin County, between 4:00 and 4:30 P.M. on a cool, windy day in mid March, 1964, by C.W. O'Brien. In the laboratory one pair was first seen at 8:30 P.M.; the couple moved at least once, but remained stationary from 9:45 to 11:30 P.M. Separation occurred between 11:30 P.M. and 7:30 A.M. The second pair apparently mated between 8:00 and 9:30 P.M. and remained in coition until after 10:30 P.M. The other copulation occurred five days after the adults were caged, when the moths had become very worn appearing. The pair was observed at 7:30 A.M., having mated sometime after 6:30 P.M.
Oviposition occurred at various times of night. One female was observed probing the nylon screen ceiling with the ovipositor at 6:00 P.M. Many eggs were deposited between 6:00 and 7:30 P.M. and between 7:30 and 10:30 P.M., and a few were deposited after 11:30 P.M.
About 200 eggs were produced by 7 females. More than 60% of these were placed on the Eriodiotyon', 21% were deposited on the nylon screen. Of those on the plant 90% were on leaves, but there was no significant difference in preference for higher or lower leaves on the stem. Even a lower leaf which was black with sooty mould (as the lower leaves of E. oalifornicum always are in the field) had 15 eggs. About two thirds of those on leaves were placed on the upperside, and all but 8 (of 80) on the uppersides were deposited along the mid vein (figs. 26-28).
In captivity, males lived 4 to 7 days, females 4 to 8 days, but water was not provided after the fifth day.
hk
arctostaphylella
Egg. - (Figs. 26-28) The eggs were elongate, and slightly flattened (slightly wider than thick), measuring about 0.40 x 0.83 to OAk x 0.90 mm.
During development the eggs turned pink by the third day. Hatching occurred after 9 to 10 days at laboratory temperatures. Eggs of the fall generation were not observed, and the overwintering stage or stages are unknown.
The eggs proved to be impervious to water. Several deposited in a field collection vial were submerged when the vial was used as a water source in the breeding jar. After five days the vial was allowed to dry. These eggs all hatched on the 11th to 13th day after their deposition.
La rva ♦ - First instar larvae were placed in salve tins with immature terminals of Eriodictyon californicum. Larvae tied two leaflets together or spun silk between a leaflet and the container. Feeding occurred as skeletonizing. By the sixth day most individuals were still in the first in-star. Six and eight day old larvae were placed on E. californicum in water vials. The plant kept well in this condition and bloomed, but larvae did not establish well. Apparently they wander considerably even though fresh leaves are available. Leaves in salve tins did not keep well and larvae had to be transferred every few days.
By the 26th day larvae were in the third instar. Feeding at this stage occurred as skeletonizing on older leaves. Larvae constructed small silken trackways between leaves.
Some larvae had reached the fourth instar by the 32nd day. No attempt was made to rear these further owing to difficulties in keeping the plant, which resulted in frequent exposure of the larvae to mouldy leaves.
Larvae collected in the field were of various stages from about half grown to mature. Most of these were not preserved. Larger larvae typically constructed shelters by spinning silk across the uppers ide of one leaf, pulling its margins towards the center. In new foliage the leaf margins were often drawn completely together, forming a tubular shelter, open at both ends. On older leaves which had hardened, the margins were drawn in only partially, forming a hammock shaped shelter with a silken mat ceiling, under which the larva rested, oriented along the midrib. The amount of visible silk varied, possibly with age of occupancy, and sometimes only a thin layer of silk covered the larva which was visible from above. Even so, and despite the fact that the larvae are brightly marked with red and black, their general light green color rendered them inconspicuous under the silk. In searching, the silk was usually seen first, and probably the larvae are thus protected from visual detection by larger p reda to rs.
On one occasion (61E13) several larvae were feeding in
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inflorescences and immature terminal leaves of E* oaliforni-Qum. None of these shelters resembled the characteristic single leaf type observed at other localities. Two or three young leaves, or sepals and flower parts were tied with silk. As in other situations, many abandoned shelters were present. In the laboratory these larvae seemed to prefer leaves, whtch were consumed before the flowers. Eriodiotyon blooms only in spring; flower parts and developing seed are not available to summer feeding larvae.
Final instar larvae of E. arctostaphylella ranged from Strongly marked, with black longitudinal bands and orange dorsal spotting, to virtually unpigmented, pale greenish with tiny dark pinacula. Some of the latter appeared to be full grown, and I had no evidence that any individual developed from one color phase to the other.
First instar: Length 1.8-2.0 mm; HC 0.27-0.30 mm, orange-brown, ocellar area black; Th'Sh pale brown; setae and Integument unpigmented.
Second instar: None preserved.
Third instar: Length 6.8 mm [1]; HC_ 0.62-0.71 mm [2] brown; Th'Sh defined laterally only; D defined, pale; DL_ indistinct, dark gray; Pin small, not surrounded by pale areas; AbdCr 6-7; AnCr 8-9.
Fourth instar: Length 10.4 mm [1]; HC 0.84-0.89 mm (parasitized) [3], 0.87-1.0 mm [5], dark orange-brown with regular, posterior darkened areas laterad and mesad on each epicranial lobe; Th'iEr. defined, mottled dark; Pin large, dark; D defined, unpigmented; DL distinct, dark to pale gray, Pin not defined by pale; L and LV not distinguished, pale and grayish mottled; AbdCr 9-12; AnCr 9-12.
Fifth instar: Length 14.3-19.4 mm [3]; HC 1.29-1.35 mm (starved) [3], 1.40-1.60 mm, orange-brown lateral and mesal markings not as well defined as In fourth Instar; ThSh unpigmented except tiny black pinacula; integumental pigment lacking to well developed, when developed, D well defined, pale orange or orange-brown; DL black, well defined with little pale mottling; L well defined; LV pale, indistinct; AbdCr 15-16 to 19-20; AnCr 19-21. Segment A9 with about 8 secondary setae on LV.
One larva from Mt. Tamalpais (unnumbered collection) exceeds above limits, representing a possible 6th instar. Length 1 8. ^ mm; H_C_ 1.73 mm; AbdC r 21, strongly biordinal; AnCr 23, biordinal.
Pupa. - Pupation in cap-tivity occurred in folds of paper toweling and in shelters in foliage similar to those occupied by larger larvae. Whether these were shelters previously used for feeding was not ascertained. The general behavioral tendency to wander and burrow into soft substrates, known
kG
discostrigella
for many other Ethmia, does not seem to be consistently practiced by E. arctostaphylella. This is the only New World species which has been recorded as using foliage for pupation. Walsingham reared the original specimen from a cocoon in foliage of Arctostaphylos, suggesting the larvae wander. In field searches I discovered cocoons of this species on the Eriodictyon at two localities in August, 1962. Five cocoons with viable pupae were located in tightly folded leaves, these resembling the typical larval shelters except more closely closed over the occupant. The dense, opaque, white outer layer of silk, covered a thin, loose silken envelope, which was evident at the ends of the leaf fol d.
One adult was reared from a dry flowering stalk of Yucca whipplei, collected near Cajon Pass, San Bernardino County, in December, 1962. The cocoon was located at the end of a tunnel several cm in length into the woody cortex, according to the collector, Eric Jessen.
Development by non-diapausing pupae required 11-13 days, including cocoon formation (60E6).
Cocoons measured about 14 mm in length and were tough with dense internal mesh. Pupae ranged 8.5"9 - 5 mm in length. The anal legs were broad with slight lateral enlargement, each distal 1y bearing 2 7 - 3 0 hooked setae which were about 0.14 mm in length. The caudal "cremaster" setae were borne in a shallow, flattened trough; all were short, probably broken in the individuals observed.
Natural enemies. - Braconid wasps of the genera Apante-les and Microaaster were reared from larvae of arctostavhul-ella at four scattered localities. Apanteles (n. sp. #\k\ of W.R.M. Mason): Alpine Lake (60E6, 3 of the 7 larvae not preserved). Microgaster (n. sp. #22 of W.R.M. Mason): Stoneyford (6 1 E3 , 1 of 6 larvae); Mt. Diablo (61G2, 2 of 2 larvae); Groveland (unnumbered collection, 1 larva).
The three parasitized larvae at Alpine Lake were still living when discovered, although each already had a braconid cocoon alongside it. The mothe larvae crawled slowly if prodded, but there appeared to be no recent feeding in the shelters. One of the three was retained alive, and it lived three days after collection. In each case the braconid larva had emerged from a hole in the side of the third abdominal segment just below the spiracle of the host.
Ethmia discostrigella (Chambers)
Anesychia discostrigella Chambers, 1877, Bull. Geol. Surv. Territories, 3:122.
This is the most commonly collected species of Ethmia in the New World. The adults are nocturnal and sometimes are
Biological studies on Ethmia
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attracted to lights in great numbers. Despite its abundance over a wide range in western North America, until recently nothing was known of its life history (Powell, 1959). E. disoostrigella and the closely related semitenebrella have diverged from the typical pattern of the genus and feed on species of Ceroooarpus (Rosaceae). In Great Basin regions of eastern California, typical disoostvigella is associated with Ceroooarpus ledifolius . In cismontane parts of the state, where the moths are generally more bluish white in appearance and the name suhoaerulea Walsingham is applicable, C. montanus {-betuloides) is the principle host. For purposes of the present discussion the two are treated together.
The moths have been flushed from foliage of Ceroooarpus at a number of sites: from C, minutiflorus at San Diego, from C. montanus in the mountains of San Diego County, Kern County, and Lake County, from C. alnifolia on Santa Cruz Island, and from C. ledifolius in the Warner Mountains, Modoc County. The study areas listed below are those which have involved the early stages. In addition, M.M. Furniss of the U.S. Forest Service sent me a large series of larvae and reared adults from Ceroooarpus ledifolius collected in Owyee County, Idaho.
Study areas. - l) Crooked Creek, 10,150 feet, White Mountains, Mono Co.; young larvae on Ceroooarpus ledifolius , July 4, 1961 (61G1); 2 females at light, July 22, 1961, retained alive (61G4). 2) Lee Vining Campground, Mono Co.; young larvae on C. ledifolius , July 19) 1961 (6 1 G 3) . 3) Lake Pillsbury, Lake Co.; 1 female at light, April 3, 1962, retained alive (6 2 D1) . h) miles east of Monitor Pass, Mono Co.; adults at light, June 30, 1962, 2 males, h females re-ta ined alive (62G3 ) .
Adu1t behavlor. - Collection records from a station in Monterey County, where a continuous sample of insects attracted to light was made throughout a season, indicated that three or more overlapping generations obtain (Powell, 1959). In Great Basin areas probably a single flight, in June and July, is normal. Under laboratory conditions pupae resulting from eggs laid in June and July in Mono County did not emerge the same season but underwent diapause, emerging the following spring.
Although the moths are easily startled into flight during the daytime, both in the. field and laboratory, even in early morning, normal activity is nocturnal. Caged females became active at dusk and engaged in oviposi tion behavior then. Whether or not lights were directly on them seemed not to affect behavior of females except they tended to congregate in the portion of the jar towards the light. The moths are active all night under favorable temperature conditions, judging from light attraction records.
Mating was not seen in the laboratory, and field observations suggest that it may occur only late at night. One
kS
diseostrige11 a
pair was taken from a congregation of scores of individuals on a vertical sheet before a 15 watt blacklight, between 12:30-2:00 A.M., east of Monitor Pass, June 25, 1962. Numerous mating pairs were observed in tree foliage at Fandango Pass, Modoc County, in May, 1970, between 9:00-11:00 A.M. by P.A. Rude.
During ovlposition females continuously walked slowly with the abdomen curled downward and prodded the substrate with the ovipositor. Females sometimes did this on the plants provided {Cercoearpus ledifolius for Mono County, C. montanus for Lake County moths), but more often used the nylon screen ceiling. In one case (62D1) nearly all 28 eggs were placed on the jar rim under the screen. In the 62G3 lot, four females deposited a total of 82 eggs; only ]k of these were on the Cercoearpus , 8 of those on the silk of an abandoned caterpillar shelter. Propensity for selection of other fibrous and roughened substrates was shown. About 30% of the eggs were placed on top of the rim of the jar, between the rim and the appressed nylon ceiling; another 25% were located on masking tape on the floor of the container (but only k eggs were placed on the smoother cardboard which was of greater area). Three were placed on a patch of cotton fibers which had stuck to the vial holding the plant. Of those on the Cercoearpus two eggs were placed on terminal stems, adjoining leaf bracts, etc., but none were laid on the larger, woody stems.
These oviposition sites suggest the possibility of use of the elongate, twisted, soft-hairy style of the fruit, which are persistent on the trees, for egg placement in the field.
Adults did not survive well in captivity, the Lake County female living 7-8 days, those from Mono County even fewer.
Egg. - The eggs were somewhat irregular in outline, evidently conforming somewhat to the substrate. Those from one 61G4 female were oval, flattened, tapering in outline toward one or both ends and measured 0.70 x 1.27 to 0.72 x ].k0 mm.
White when first deposited, the eggs turn bright pink on the second day, remaining so until just prior to hatching when the dark larval head capsule becomes visible and the eggshell looks whitish, semiopaque.
Hatching occurred in 9 days in July, in 10 days in April at laboratory temperatures.
Larva. - First instar larvae (62G3) were placed on Cercoearpus ledifolius from Monitor Pass, which had been in water 10 days. Nine days later some had reached the second instar. Larvae at this stage were inconspicuous, living in crotches of twigs and subsessile leaves, with little visible silk. Feeding occurred as small round skeletonized spots,
Biological studies on Ethmia
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mostly on undersides and on apical half of leaves. Young larvae were easily disturbed and quickly dropped down on silken threads at the slightest stimulus.
Ceroocarpus ledifolius from the collection site was provided at 9, 19, and 35 days, after refrigeration, and seemed to take up water and serve adequately as larval food.
By the 161 h day larvae had reached the third instar. By this time, and thereafter, the larvae were extremely reactive to external stimuli - prodding caused them to wriggle backwards extremely quickly, so as to appear to jump, often going 10 to 20 cm on a flat surface.
At 20 days most individuals were in the fourth instar, and all larvae had reached the penultimate instar by the 25th day.
By the 35th day all larvae had reached the last instar. As in the case of E. plagiobothrae, two distinct color phases were shown: a paler one showing bluish dorsolateral bands and a lighter orange dorsal band, and a dark form, which was more common, with the dorsal band yellow-orange to rust-orange, the dorsolateral bands black.
The final full grown larvae, in the pale state, were preserved on the 4lst day.
Larvae collected as second instar at Crooked Creek required a longer period to mature, probably owing to poorer food conditions. These larvae were provided with cut twigs of C. ledifolius in salve tins. After 13 days fresh C. mon-tanus from Contra Costa County was provided. All subsequent feeding took place on this plant. Intermittently the plant material dried, leaves frozen for 14 days were provided,and fresh C. montanus was provided again on the 36th day.
The first cocoon was formed 48 days after collection of second instar larvae, and the last larva died after the 58th day when additional foodplant from the freezer was added.
There appear to be five instars (f„i g . 6). The rather wide spread in head capsule measurements in the final two instars may have been caused by differential laboratory conditions, since field collected larvae were taken in young instars.
First instar (62D1); Length 2.3-3-0 mm; HC_ 0.31-0.30 mm, pale tan, slight brownish spots; Pin visible on thorax. (61G4): Length 3.1-3.3 mm; HC 0.3^-0.38 mm, pale tan with brown dorsolateral and venterolateral spots; ThSh brownish laterally; Pin brownish, diminishing on posterior half of abdomen. (62G3): Length 2.7-3.1 (one day) to 4.2 mm (9 days); HC_ 0.36-0.39 mm, pale tan becoming darker at 9 days; Pin pale brownish, becoming darker and well defined on whole abdomen.
50
disoostrige11a
Later instars are characterized on the basis of 61G1 and 62G3 specimens.
Second instav: Length 4 . 7 (Teneral) - 6.0 mm; RC_ 0.50-0.55 mm, dark brown without appreciable mottling; Fin dark brown, those of ThSh larger; integument otherwise without pigment, setae dark; AbdCr 6; AnCr 8.
Third instav: Length 6.7-8.0 mm; HC^ 0.60-0.91 mm, yellow-tan with faint brownish mottling and dark and frontal spots; Pin dark, large; D well defined, pale orange; IXL heavily mottled, gray to blackish with a paler (less densely mottled) median streak; L not well defined, LV with almost no pigment; AbdCr 10-11 "Crarely L4); AnCr 11-13-
Fourth ins tar: Length 9.1-15.1 mm; HC 0.96-1.24 mm, yellowish with black adfrontal spots;Pin dark; D well defined, orange with blackish spots; DL well defined, blackish, darker than 3rd instar, obscuring pinacula; L well defined, pale; LV almost as dark as 'DL, Pin only slightly darker; AbdCr 13-17; AnCr 18-22, biordinal.
Fifth instar: Length 15.9-21.5 mm; H<3 1.46-1.68 mm, orange, mottled darker orange along posterior margins; Pin dark, relatively smaller than preceding instars; D well defined, dark orange (dark phase) or yellow-orange "Cpale phase); DL. pale gray or blackish, less densely mottled than 4th instar, densest at D and L margins; L pale, not well defined; LV mottled gray, pale to dark, not well defined; AbdCr 23-30 (usually 28-30), biordinal mesally; AnCr 26-30, biordinal. Segments Al, A2, A9 with 1-3 small secondary setae on LV.
Pupa. - Cocoons were constructed in the corners of salve tins, incorporating a few plant parts. One individual used a rolled leaf. Pupation occurred within ten days after starting construction of the cocoon. Those pupating in mid and late August went into diapause and were housed in the dark salve tins at laboratory temperatures overwinter. Emergence occurred in late April and early May, probably about a month ahead of the flight period in Mono County.
Pupae ranged 7.7~8.7 mm in length (61G3) . The anal legs protruded ventrally more strongly than in most other species and were relatively smaller, widely spaced, and strongly diverging, sometimes extending almost directly ventrad and lat-erad. There were 1 "7 — 1 8 (rarely 12) hooked setae on each anal leg. The caudal "cremaster" setae were extremely long and frail, up to 1.4 mm long (twice as long as the hooked setae of the anal legs), borne on weakly to well developed lateral humps. Usually they were broken off in the cocoon.
Biological studies on Ethmia
51
Ethmia semitenebrella Dyar
Ethmia semitenebrella Dyar, 1902, Jour. N. Y. Ent. Soc, 10:204.
As discussed elsewhere (Powell, 1959) this and the preceding species, discostrigella are closely related. Subsequent studies have shown that the two share similar biologies, using species of Cercocarpus as hosts. In the original description Dyar mentioned that E. semitenebrella was reared from c. parviflorus in Arizona.
S tu dy a rea . - Four miles east of Monitor Pass, Mono Co.; adults at light, June 2k and 30, 1962, 2 males, 6 females retained alive on latter date (62G2).
Adu1t behav i or. - This species is geographically and ecologically restricted compared to discostrigella, and semitenebrella appears to have only a single annual flight.
The moths are nocturnal. Adults were caged after 36 hours storage in a field ice box. They became active at dusk and showed a similar activity pattern to discostrigella from the same locality. Neither oviposition nor mating was observed. Females behaved similarly to those of discostrigella in prodding the ovipositor through the nylon screen. All the semitenebrella died 5-6 days after collection.
Only kk eggs were deposited by the 6 females. As in the case of discostrigella , a preference for roughened surfaces was shown, but 30 of the kk were deposited on the floor of the jar, possibly in part a function of age or weakening of the females. All but 3 of these were laid on masking tape or in a crease in the cardboard. Only 3 eggs were deposited on the Cercocarpus. Seven eggs were placed on the nylon screen, but none were at the rim of the jar adjacent to or under the appressed nylon, a site used for 30% of discostrigella eggs.
Egg. - As in discostrigella , eggs of the present species were not regularly rectangulate or ovate, but varied to some extent with the substrate, often tapering towards one end. Those deposited on the nylon screen measured 0.66 x 1.kO to 0.70 x 1.32 mm.
All turned uniform dull reddish prior to the fifth day, darkening only shortly before eclos ion. Eggs began hatching July 13, about 10.5-11 days after oviposition. Most were transported on a field trip July 13"15; and those remaining unhatched survived transit in an uncooled car at h0° C air temperature, conditions which were lethal to young larvae, hatching between 8:00 and 11:00 A.M. the following day, about 11 days incubation.
La rva . - First instar larvae were placed on terminals of Cercocarpus ledifolius which had been in refrigeration 12
52
semitenebrella
days. Those emerging prior to July 15 did not survive automobile transport in 40° C air temperature. The remaining first instars hatched July 16 and were placed on 15 day old refrigerated C. ledifolius . They showed a marked tendency for positive phototropism during daylight hours, crawling to the top of a vial, away from leaves or to the side of a branch toward the light.
Larvae established in small webs in crotches of leaves and twigs or between leaves. Larvae had reached the second instar before the 14th day. Additional C. ledifolius from Monitor Pass was provided on the 14 th day, after 30 days in refrigerat ion.
The third instar was reached on the 15th to 161h day, and the fourth by the 20th day. Although the original branch had become covered with fine mold by 10-14 days, larvae had not left it and were transferred to the fresher fol iage which had been added to the bouquet 6 days previously. At this time evidence of larvae had become quite noticeable, with considerable webbing which at times collected frass on the uppersides of leaves.
The final instar was reached by the 29th day and the last full grown larva was preserved on the 35th day. To the unaided eye mature larvae appeared steel blue-gray with bright yellow dorsal and lateral bands. The venter was bright pink, differing from discostrigella which had a pale venter.
Too few specimens were preserved to enable precise determination of the number of instars.
First instar: Length 3.3-3.5 mm; HC_ 0.45-0.47 mm, pale tan with black ocellar area, becoming entirely dark brown at maturity. No integumental pigment.
Second instar: Length 8.2 mm [1]; HC_ 0.64-0.66 mm [5], pale brown, mottled darker; Pin brown, rather large; integument otherwise unpigmented, setae black; Ab.dCr 8-11; AnCr 11.
Penultimate instar (none preserved): Length 9-10 mm; HC^ 1.04-1.28 mm [2], pale orange, shaded brownish, not strongly mottled; D yellowish; DL pale bluish.
Final instar [3]: Length 15-9-23.0 mm; EC_ 1.70-1.87 mm, orange, mottled with white laterally; Pin dark brown, scarcely differentiated from integumental dark areas, strongly contrasting in pale areas; D and L distinct yellow; DL, dark steel gray to blue-gray, irregularly mottled with small white spots; LV only lightly mottled; V bright pink, a subintegu-mental color; AbdCr 28-30 or 32-34; AnCr 30-34. Segment A9 with 12-14 small secondary setae on a sclerotized patch extending 1/2 the distance to V seta.
Biological studies on Ethmia
53
Ethmia timberlakei Powell
Ethmia timbevldkei Powell, 1971, U. Calif. Publ. Ent.; in press.
This species is closely related to gevanella Barnes and Busck, and may prove to represent a segregate of that species when more is known of both. These and related species differ from most other Ethmia in life cycle, feeding as larvae in spring, aestivating as pupae, and flying in fall. The biology of E. macelhosiella Busck, a member of the group in eastern United States, was studied by Busck and Heinrich (1922).
S tudy a rea . - Hill back of Citrus Experiment Station, University of California, Riverside; larvae on Phaoelia vam-osissima var. suffrutesoens, March 21 and 24, 1961 (P.H. Timberlake, R.L. Langston and J. Powell) (61C12, C13) ; larvae on P. ramosissima} May 13, 1962 (62E7).
Adu1t Behavior. - Only a single individual has been field collected, at light between 8:30 and 10:00 P.M. on October 17, I960, near Desert Springs, San Bernardino County. Closely related species have been taken at lights between mid September (8000 feet elevation) and November (1000 feet). Adults of E. timberlakei emerged prior to November 8 (61C12) and between November 1 and 19 (62E7).
Reared moths were observed in late November, 19 6 2. One male and two females already. In worn condition were caged in a dry jar with debris and cocoons from the original rearing container. The moths were inactive during daylight and appeared reluctant to move at night with lights on in the room. At this time they moved only by short, quick "jumps" when disturbed by the observer. They were active at night with the lights off•
Fertile eggs were deposited prior to November 19, but not after that date. Although no water was available, the moths lived 11-14 days after first observed, when already in worn cond i t i on .
Numerous eggs were deposited, primarily in aggregated groups, not in any systematic arrangement, around the glass side of the jar near the upper rim. A few scattered eggs were laid on the dry Phaoelia foliage and paper toweling. Most had turned reddish by November 19 and apparently entered diapause.
Although kept in a dry container at laboratory temperatures, about half of the eggs hatched at sporadic intervals during the following spring.
Larva. - In late March, 1961, larvae of at least the final three instars were present on Phaoelia ramosissima. Most were in the last instar. In mid May, 1962, only full
51
timbevlakei
grown larvae were present, and evidences of feeding indicated that most had already left the plants.
Larvae of E. timbevlakei differed in habits from most other species studied (including nadia at the same site) by living exposed on the leaves, without any shelter. During the daytime most were concentrated towards the lower portions of the dense foodplant clumps, rather than exposed in direct sunlight. In several cases the bushes grew adjacent to large boulders on a southerly exposure. The caterpillars rested toward the back of the clump, in the shade, where the foliage was most dense. Almost all perched on the undersides of stems or main midrib of the compound leaves.
Presence of larvae was evidenced by scattered frass toward the distal end of the branch, evidently held by the viscid hairiness of the plant. Probably larvae moved outward at night to feed, and rested under the stems inactively during the day.
A few small webs were found on undersides of leaves, with associated head capsules. It is assumed these were moulting webs, but it may be that early instars, which were not observed, construct weak shelters.
In rearing, larvae were housed in 85 x 100 mm jars in field conditions for 7 to 10 days and severe moisture condensation and moulding of foodplant resulted. However, no disease symptoms developed. Fresh Phacelia, presumed to be ramosissima, from San Diego County, was provided on the 5th day, but little or no feeding occurred on it.
Most of the larvae successfully formed cocoons by the 12th day after collection.
Second instav (?) [2]: Length 6.0 mm; HC_ 0.47 mm, entirely dark brown; Pin tiny, dark; almost no other integu-mental color; D, L weakly white, Abdcr 8-10; AnCr 7-
Third instav (?): Length 6.0-7.8 mm (teneral), 9.5-11.0 mm; HC! 0.61-0.68 mm (teneral and parasitized), 0.73-0.83 mm, dark brown with pale mottling anteriorly; D defined, whitish; PL pale gray; Pin black,small; integument otherwise unpig^ mented; AbdCr B^ll; AnCr 7-11 (usually 10-11).
Penultimate instav. Length 10.4-12.0 mm; HC 0.87-0.97 mm, dark brown posteriorly, whitish anteriorly; D well defined, yellowish; VL_ mottled grayish (appearing bluish green in life); L distinct, yellowish; Pin dark, small; AbdCr 14-16; AnCr 15-16.
Final instav. Length 9-5 mm (unfed?), 15.6-17.2 mm; HC: 1.0-1.23 mm, white, mottled with brownish black posteriorly; ThSh defined by small blackish mottling; Pin small, black; D yellow; almost no other integumental color, EXL pale grayish, lightly mottled (appearing pale bluish green in life), leav-
Biological studies on Ethmia
55
ing irregular unpigmented areas around pinacula; AbdCr 14-20 (usually 17-20); AnCr 16-21.
Pupa. - Cocoon formation occurred mainly in folds of paper toweling in the rearing container; a few were formed in mouldy foliage. Pupae were formed soon after cocoon construction. At least one pupa was present by April 5, 12 days after the larvae were collected.
In the field no cocoons were located on the foliage, even in late season condition, in May, 1962. The closely related E. macelhosiella was reported to burrow into bark of trees and logs for pupation (Busck and Heinrich, 1922). At Riverside, the dry chaparral association contains no plants with large woody trunks and appreciable thickness of bark. The pithy, dry stems of previous years1 Phaoelia growth was the only likely site evident in which larvae might burrow, but search of a large random sample of preceding years1 stems revealed no abandoned cocoons.
The cocoons were about 11-12 mm long and exteriorly were papyrus-like in consistency, not translucent and could be torn like paper. Inside there was little loose mesh, and pupal shells could be easily extracted without breakage.
Pupae measured 7-5~8.2 mm in length. The cremaster setae were observed intact on several individuals, about 0.11 mm in length, very frail, curving towards the tip. The anal legs were widely spaced (0.33 mm apart at base), not diverging, and short, the free part only about 0.23 mm in length. The distal end bore 18-20 anchor setae in several examples.
Cocoons were stored in dry jars at room temperature and successful emergence occurred from nearly all, during a three week period in late October and the beginning of November.
Natural enemies. - The colony at Riverside was affected by a braconid, an undescribed species of Miorogaster (n. sp. #8 of W.R.M. Mason). In the laboratory Ethmia larvae reached the final instar prior to emergence of the braconid larvae. Numerous wasps were reared, and it is assumed that each affected the host solitarily. However, no estimate of the proportion of the sample which was parasitized was made. Under laboratory conditions Miorogaster adults emerged in May, apparently out of phase with any available stage of the e t h m i. i d .
56
Literature Cited
Braun, A.F., 1921. Two weeks collecting in Glacier National Park. Proc. Acad. Nat. Sc?., Phila., 73:1-23.
Busck, A. and C. Heinrich, 1922. Life history of Ethmia
maoelhosiella Busck. Proc. Ent. Soc. Wash., 24(l):l-9.
Cuming, F.G., 1941. The distribution, life history, and economic importance of the winter moth, Operophtera bru-mata (L.) (Lepidoptera, Geometridae) in Nova Scotia. Canad. Ent., 92(3):13 5-141 .
Dyar, H.G., 1902. A review of the genus Ethmia with descriptions of new species. J. New York Ent. Soc., 10:202-208.
Keifer, H.H., 1936. California MIcro1epidoptera VIM. Bull. So. Calif. Acad. Sci., 35:9-29.
Lawrence, J.F. and J.A. Powell, 1969. Host relationships in North American fungus feeding moths ( Lepidoptera:Oeco-phoridae, 0inophi 1 idae , Tineidae). Bull. Mus. Comp. Zool., Harvard, 138:29-51.
Parker, F.D. and R.M. Bohart, 1966. Host-parasite associations in some twig nesting Hymenoptera from North America. Pan-Pacific Ent., 42(2) : 91-98.
Powell, J.A., 1959. Studies on the genus Ethmia Huebner in western North America ( Lepidoptera:Ge1echioidea) . Was-mann J. Biol., 17(l):133-151.
1962. Some observations on the minimum temperature threshold of moth activity at light. Presented at 12th Ann. Meeting Pacific Slope Br., Lepidopterists' Soc., Santa Barbara tunpub1ished].
1964. Biological and taxonomic studies on tor-tricine moths, with reference to the species in California (Lepidoptera:Tortricidae). U. Calif. Publ. Ent., 32, 318pp.
1971. Systematic monograph of New World eth-miid moths (Lepidoptera:Gelechioidea). U. Calif. Publ. Ent., in press .
57
Host Plant Index
Bo rag i na ceae
Amsinckia intermedia F.&.M.............15, 32
A. lunaris MacBride..................23
A. speotabilis F.&.M..................23
A. tessellata Gray...................32
Cryptantha circumcis 3a (H.&A.) Johnst.........21
C. intermedia (Gray) Greene..............30
Plagiobothrys nothofulvus (Gray) Gray.....13, 23, 26
P. tenellus (Nutt.) Gray................26
Hyd rophy1 1aceae
Eriodiotyon californioum (H.&A.) Greene........hi
Nemophila maculata Benth................10
N. menziesii H . & A................9 , 11
Phacelia californica Cham.............23, 27
P. calthifolia Brand .................40
P. crenulata Torrey..................40
P. distans Benth..........8, 10, 15, 17, 36, 39
P. distans var. australis Brand............21
P. ramosissima Dougl..................35
P. ramosissima var. suffrutescens Parry......38, 53
P. tanacetifolia Benth.............10, 11, 39
Ros aceae
Cercocarpus ledifolius Nutt............h~J , 51
C. montanus Raf....................A9
C. parviflorus Wooten.................51
S c roph u1 a r i aceae
Collinsia heterophylla Bulst
13
58
Explanation of Figures
Figs. 1-6, larval head capsule measurements in six species of Ethmia. Each square represents one individual. Diagona1 - 1ined squares represent larvae reared from eggs in lab; solid, half-solid, and shaded squares represent field collected larvae. Rearing lot numbers refer to data given in text. Size scale (mm) is the same in figures 1-5.
1. E. plagiobothrae Powell
2. E. albitogata Walsingham
3- E. b. brevistriga Clarke
**. E. soylla Powel1
5. E. a. albistrigella (Walsingham); dotted line indicates hypothetical size of first instar.
6. E. disoostrigella (Chambers)
59
0 0
0.5
0 0
JLi sJUli
.y_
y .L A .
.-. . '■_ .'xlli
\a H 0 mSI
0.5
J hi ' . . j -. r^-
mm 0.5 1.0
|
^ 62C2 B |
69D58 |
|
|
P 64D10 | |
61D4 |
1 |
|
f/l 68B178 |
||
|
P 63E1 |
2 |
|
|
fl |
61D2 |
|
|
P |
61E21 |
3 |
|
0 |
69C90 |
|
|
P |
69D60 4 ^ 62F11 P 62H3 |
|
|
0 0 |
0 |
5 |
|
^ 62G3 |
||
|
B 61G3 |
||
|
P 61 Gl |
||
|
EC |
K |
ZB 00 0 |
|
1.5 |
6 |
60
Explanation of Figures
Fig. 7, final instar larva of Ethmia oharybdis Powell; head and thoracic segments I-II, dorsolateral aspect; abdominal segments 6-10, lateral aspect. Body regions: D = dorsal, DL = dorso1 ateral , L = lateral, LV = 1 ateroventra1 .
Figs. 8, 9, pupa of E. semilugens (Zeller); 8, ventral aspect; 9, lateral aspect.
Fig. 10, pupa of E. soylla Powell, ventral aspect.
Figs. 11, 12, egg of E. coqwillettella Busck, illustrating placement on nylon mesh, a substrate commonly selected by females of various species under cage conditions; 11, ventral aspect; 12, lateral aspect. Length of egg = approximately 0.80 mm.
61
62
Explanation of Figures
Figs. 13-20, eggs of Ethmia (approximate magnification indicated in parentheses).
13, 1^, eggs of E. soylla Powell (69C90) in petiole axils of Collinsia heterophylla (hx).
15-17, scanning electron micrographs of E. soylla eggs and detail of chorion structure (69C90); 15, (60x); 16, (300x) ; 17, (1200x) .
18-20, eggs of E. minuta Powell (6 3 D18) in unopened, hispid inflorescences of Cryptantha intermedia; 18, (12.5x) ; 19, (7x); 20, (7x).
63
P
19
64
Explanation of Figures
Figs. 21-24, eggs of Ethmia on natural plant substrates (approximate magnification indicated in parentheses).
21-23, eggs of E. b. bvevistriga C1 arke (6 1 D2) ; 21 on sand-encrusted lower branch of Phaoelia distans (7x); 22, on underside of mid-vein of P. distans compound leaf (7x); 23, same eggs (12.5x).
24, eggs of E. plagiobothrae Powell (62C2) on underside of Phaoelia californica leaf, an abnormal host which was partially accepted by females but not accepted by larvae (7.5x).
65
JEW -^ ^W
HlSr1*'
66
Explanation of Figures
Figs. 25-29, eggs of Ethmia on natural plant substrates (approximate magnification indicated in parentheses).
25, eggs of E. plagiobothrae Powell (62C2) on setose stem of Phaoelia califovnicay an abnormal host (13.5x) .
26-28, eggs of J?, avctostaphylella (Walsingham) (61 D3) on Eriodictyon californicum; 26, on lower branch encrusted with sooty-mold (7.5x) (the lower foliage commonly becomes covered with sooty-mold owing to glandular secretions of this plant); 27, on mid-vein, upperside of leaf (7.5x); 28, same egg s (12x) .
67