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Journal of the Lepidopterists' Society

Lees, D. R., E. R. Creed & J. G. Duckett. 1973. Atmospheric pollution and

industrial melanism. Heredity 30: 227-232. Muller, J. 1960. A new melanic form of Catocala connubialis from New Jersey

(Noctuidae). J. Lepid. Soc. 14: 177-178. Owen, D. F. 1961. Industrial melanism in North American moths. Amer. Nat.

95: 227-233. ----------. 1962. The evolution of melanism in six species of North American

geometrid moths. Ann. Entomol. Soc. Amer. 55: 695-703. ---------- & M. S. Adams. 1963. The evolution of melanism in a population of

Catocala ilia (Noctuidae). J. Lepid. Soc. 17: 159-162. Remington, C. L. 1958. Genetics of populations of Lepidoptera. Proc. 10th Int.

Congr. Entomol. (1956) 2: 787-805. Sargent, T. D. 1969. Background selections of the pale and melanic forms of the

cryptic moth, Phigalia titea (Cramer). Nature, Lond. 222: 585-586. ----------. 1971. Melanism in Phigalia titea (Cramer) (Lepidoptera: Geometridae).

J. N. Y. Entomol. Soc. 79: 122-129.

BIOLOGY AND IMMATURE STAGES OF SCHINIA MITIS (GROTE) (NOCTUIDAE)1

D. H. Habeck,2 R. T. Arbogast3 and L. D. Cline3

Department of Entomology and Nematology, University of Florida, Gainesville, Florida 32601

Schinia mitis (Grote) occurs from central Florida, north to Georgia, and west to eastern Texas (Hardwick, 1958). Most of the specimens Hardwick examined were collected in April, May, and June, but a few were collected in September and November. Kimball (1965) listed Florida records from March to June. Forbes (1954) gave the foodplant as Sitilias caroliniana Walt. [= Carolina false dandelion, Pyrrhopappus carolinianus (Walt.)DC]. Hardwick (1958) figured the lateral aspect of the egg and design of the chorion and gave a description and dimensions based on eggs dissected from preserved or dried females. Ganyard & Brady (1972) reported that males were attracted to virgin females of Indian meal moth, Plodia interpunctella (Hiibner); almond moth, Cadra cautella (Walker); and fall armyworm, Spodoptera frugiperda (J. E. Smith), in field studies at Watkinsville, Georgia. No other published information was found on this species.

1 Florida Agricultural Experiment Station Journal Series No. 5035. Received for publication.

2 Research Associate, Florida State Collection of Arthropods.

3 Present address: USDA, Stored-Product Insects R&D Laboratory, Box 5125, Savannah, Georgia 31403.

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Fig. 1. Schinia mitis egg on inside of involucre of Pyrrhopappus carolinianus (Walt.) DC.

Schinia mitis is a day-flying heliothidine moth. It is active only for a few hours in the morning when the flowers of the Carolina false dandelion are open. Moths fly rapidly from flower to flower but are easily netted while on a flower. On hot sunny days, all the flowers may be closed by 1000, whereas on cooler cloudy days, flowers may remain open until about noon. When the flowers are closed the moths usually rest facing downward on the stem or side of the receptacle. Occasionally, a moth was observed resting head downward in a flower. Mating apparently occurs on open flowers since mating pairs were frequently observed there from about 0700 to 0945, although mating probably also occurs earlier. Ovipositing females extend their abdomen downward between the florets and deposit eggs either on the developing ovaries or more often on the inside of the involucre (Fig. 1).

During 1967, flowers of the Carolina false dandelion began to appear in late February in the Gainesville area; and a few blooms were observed as late as October. Most flowers appeared between mid-April and mid-June. Flowers collected on 18 and 24 March contained no larvae, but some eggs were found in the latter collection. Thereafter weekly collections consisting of 150 flower heads (50 open, 50 closed yellow, and 50 closed white) were made through 11 August, and all samples con-

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Table 1. Seasonal distribution and abundance of Schinia mitis eggs and larvae in weekly collections of flowers of Carolina false dandelion. Gainesville, Florida. 1967.

tained eggs and/or larvae of S. mitis (Table 1). Flowers became scarce after that and partial samples collected on 18 and 30 August and on 22 September were negative. This agrees with the results of Ganyard & Brady (1972) at Watkinsville, Georgia (ca. 300 mi NNW of the Gainesville area) where no S. mitis males were collected in traps placed in the field after about 10 September.

Open flower heads contained mostly eggs, but almost no eggs were found in the closed white heads, although larvae were common there. In the yellow closed heads, both eggs and larvae were commonly found. This is not surprising in view of the development of both the insect and the flower. Sixty flower buds were tagged and checked daily to determine the flowering period. Each flower was open only 2-3 days followed by a closed period during which the seeds developed. During this closed period, the flower heads could be separated into a yellow phase (1.5-3.0 days) and a white phase (4.0-7.5 days) after which the head opened up and the seeds were blown away. Therefore, since oviposition cannot occur until the flowers open and the eggs do not

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Fig. 2. Pupa and larva of Schinia mitis: A, B, C. ventral, dorsal and lateral view of female pupa; D. lateral view of mature larva.

hatch until the flower closes, there are only about 10 days in which the flower head is available for food. Since larval growth required a minimum of 13 days, the larvae must inhabit at least two flowers to complete their development. Large larvae were occasionally observed in open flowers or yellow closed flowers in the field.

The sex ratio of 43 moths collected from flowers between 10 May and 30 June was nearly 1:1 (21 <$, 22 5 ). Of 19 females examined, all had mated: 14 once, 4 twice and 1 three times. Four of the females contained over 40 fully developed eggs, with one having 75.

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On 2 occasions vespid wasps were observed burrowing into flower heads. On each occasion, when the wasp withdrew it was dragging a mature larva which it promptly stung. One of the wasps was captured and identified as Pterocheilus texanus Cresson. Predation by these and possibly other wasps apparently was not unusual since flowers were seen frequently that had been torn open in a similar way. The only other enemy observed was a crab spider, Mimusops sp., which had captured an adult moth on an open flower.

Life History

Eggs were collected from field flowers and placed singly in test tubes with whole or partial flowers and kept at 25° C and 14:10 light:dark photoperiod. All field collected eggs hatched within 3 days. Although 24 larvae were reared to the pupal stage, only 18 emerged as adults, the others apparently entering diapause. The larval stage required 13-18 days (avg. 15.3) and the pupal stage 9-17 days (avg. 12.9). Daily observations of 11 individuals revealed eight with 4 larval instars and three with 5 instars. The average duration of the stadia was 3.4, 2.4, 2.4, and 7.0 for 4 instars and 4.3, 2.0, 2.0, 2.0 and 7.0 days for 5 instars. Development from hatching to adult emergence required 22-32 days (avg. 28.0).

Egg (Fig. 1). Light green, closely matching color of inside of involucre. Color

fairly constant at least until larva inside becomes visible. Dimensions of egg:

length 0.71 ± 0.03 mm, width 0.48 ± 0.03 mm (23 eggs).

Larva. Spicules, which become progressively more conspicious in later instars,

present on bodies of all larvae. Spicules pale except in reddish transverse bands

where they are black.

First Instar. Head capsule width: 0.39 ± 0.03 mm (n = 29). Head pale yellowish-brown. Ocellar area dark brown. Body yellowish-white. A faint yellowish-pink transverse band present on metathorax and abdominal segments 1-8 in some specimens. Prothoracic shield, thoracic legs, anal shield, lateral sclerites on prolegs, and pinacula grayish-brown.

Second Instar. Head capsule width: 0.65 ± 0.04 mm (n =z 28). Head light brown suffused with slightly darker markings. Ocellar area dark brown. Frons and adfrontals often lighter. Body pale orange except for whitish prothorax. Whitish spot dorsad and ventrad of seta D2 on abdominal segments. Prothoracic shield dark brown with 4 irregular incompletely separated black spots. Thoracic legs and pinacula dark brown. Anal shield and lateral sclerites on prolegs grayish-brown.

Third Instar. Head capsule width: 1.05 ± 0.06 mm (n = 29). Head yellowish-brown, suffused with light brown markings. Ocellar area dark brown to black. Body reddish-brown, except lateral aspects of 10th abdominal segment whitish. Each abdominal segment with whitish spot dorsad and ventrad of seta D2. Metathorax with similar whitish spots plus a whitish subspiracular spot which is also present on abdominal segments 1 and 2. On mesothorax a whitish spot ventrad of seta D2 forms a whitish line extending anteriorly to the prothoracic shield. Prothoracic shield white with 6 black spots. Thoracic legs grayish-brown. Pinacula grayish-brown to brown. Lateral sclerites on ab-

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dominal prolegs light grayish-brown. Anal shield and lateral sclerites on anal prolegs dark grayish-brown.

Fourth and Fifth Instar (Fig. 2 D). Head yellowish-brown suffused with light brown markings. Frons and adfrontals paler. Ocellar area black. Body creamy white with maroon transverse band on anterior half of meso- and meta-thorax and abdominal segments 1-9. Bands on mesothorax and 9th abdominal segment noticeably paler. Prothoracic shield whitish with 6 irregular black spots. Thoracic legs pale basally gradually darkening to grayish-brown on tarsus. Anal shield pale yellowish-brown. Spiracles dark brown with black peritreme. Pre-spiracular sclerite black, pinacula brown.

Pupa (Fig. 2 A, B, C). Lightly sclerotized, light orangish-brown. Spiracles in shallow depression, rims of spiracles projecting above cuticular surface. Anterior margins of abdominal segments 5, 6, and 7 strongly pitted. Proboscis length variable, exposing metathoracic legs as figured or extending completely to apex of wings. Cremaster consisting of 2 elongate spines curving slightly ventrad.

Acknowledgments

The assistance of Mrs. Sandra Shuler in various phases of this study and of Mrs. Phyllis Habeck for the illustrations is gratefully acknowledged. Identification of the wasp was by Dr. Eric Grissell and the spider by Dr. Karl Stone.

Literature Cited

Forbes, W. T. M. 1954. Lepidoptera of New York and Neighboring States. Part

3. Cornell Univ. Agr. Exp. Sta. Mem. 329. 433 p. Ganyard, M. C. & U. E. Brady. 1972. Interspecific attraction in Lepidoptera

in the field. Ann. Entomol. Soc. Amer. 65: 1279-1282. Hard wick, D. F. 1958. Taxonomy, life history, and habits of the elliptoid-eyed

species of Schinia (Lepidoptera: Noctuidae), with notes on the Heliothidinae.

Can. Entomol. Suppl. 6: 116 p. Kimball, C. P. 1965. The Lepidoptera of Florida; An annotated checklist. Artho-

pods of Florida and neighboring land areas. 1. Fla. Dept. Agr., Gainesville.

363 p.

A FURTHER FIELD NOTE ON ISOPARCE CUPRESSI (SPHINGIDAE)

A description of the larva of Isoparce cupressi (Bdv.) was given by the author (1973, J. Lepid. Soc. 27: 1-8), accompanied in the same issue by a field note by Van Buskirk (p. 83-84). Both articles omitted mention of a larval character brought to notice in the caterpillars collected by Van Buskirk near McClellanville, South Carolina. In my description of the development of the larva, much attention was given to the brown on the dorsal stripe and on the spiracular areas. In Van Buskirk's specimens, many of them showed no such brown except for the dorsal horn and on the second thoracic spiracle. Instead, the areas mentioned showed the same yellowish white of the lateral lunules. All degrees between the two extremes were seen in the wild larvae. Van Buskirk's wild caterpillars included various instars collected over a very few days, and so represented the offspring of several different females, leading to the conclusion that the natural coloration of the larva is variable in this respect.

Richard B. Dominick, The Charleston Museum, Charleston, South Carolina 29401.