The text below is grayed out because it is not intended to be read. It is a necessarily imperfect OCR of the original and is only used by a search engine.
Volume 53, Number 3
127
Gerberg, E. J. & R. H. Arnett Jr. 1989. Florida butterflies. Natl.
Sci. Pubis., Inc. Baltimore, Maryland. 90 pp. Hong, J. W. & A. P. Platt. 1975. Critical photoperiod and day
length threshold differences between northern and southern
populations of the butterfly Limenitis archippus. J. Insect
Physiol. 21:1159-1165. Kimball, C. P. 1965. Arthropods of Florida and neighboring land
areas. Lepidoptera of Florida. Vol. 1. Florida Dept. Agric. Div.
Plant Industry. Gainesville, Florida. 168 pp. Minno, M. C. & T. C. Emmel. 1993. Butterflies of the Florida
Keys. Active Record Scientific Publishers, Inc., Gainesville,
Florida. 168 pp. Platt, A. P. 1989. Possible photosensitivity of the abdominal
saddlepatch region of Limenitis archippus larvae (Lepidoptera:
Nymphalidae). Mol. Entomol. 3:57-66. Platt, A. P. & J. R. Maudsley. 1994. Continued interspecific
hybridization between Limenitis (Basilarchia) arthemis
astyanax and L. (B.) archippus in the southeastern U.S.
(Nymphalidae). J. Lepid. Soc. 48(3):190-198. Remington, C. T. 1958. Genetics of populations of Lepidoptera.
Proc. Tenth, Intl. Congr. Entomol. 2:787-805. Remington, C. L. 1968. Suture-zones of hybrid interaction
between recently joined biotas. Evol. Biol. 2:321-428.
Journal of the Lepidopterists' Society 53(3), 1999, 127-129
Additional key words: semivoltine, biennialism.
The nearctic genus Sthenopis Packard (Hepialidae) currently contains five species (Davis 1983), of which S. argenteomaculatus (Harris), S. purpurascens (Packard) and S. quadriguttatus (Grote) purportedly occur in Alberta (Bowman 1951). Despite their large size and peculiar habits, little is known about their biology and specimens are rare in collections. The purpose of this note is to report on the adult biology and distribution of the genus in Alberta. S. argenteomaculatus does not occur in Alberta, and S. quadriguttatus was placed into synonomy with S. purpurascens by Nielsen et al. (1999) based on morphological characteristics. Our observations of sympatric populations of S. purpurascens and S. quadriguttatus color morphs support this view.
Specimens examined and study sites. A total of 96 Sthenopis specimens from Alberta and Saskatchewan were examined, from the following sources: Northern Forestry Centre (NFC) (Canadian Forest Service, Edmonton), University of Alberta Strickland Museum (UASM) and the private collections of the authors.
Behavior observations and habitat notes were based on the following Alberta localities: Finnegan Ferry (51°8'N, 112°5'W), 15-July-1985 (DDL); Didsbury (51°40'N, 114°8,W), 23-July-1987 (BCS); 23 km N. of Lac La Biche (54°55'N, m'WW), 22-July-1997 (BCS); Rock Island Lake (55°35'N, 113°25'W), 26-July-1997 (BCS); Gregoire Lake Provincial Park (56°35'N, llFlCW), 24-July-1997 (BCS); 10 km S Cooking Lake (53°21'N, m'WW), 28-31-July-1997 (DDL, BCS); Palisades Research Centre, Jasper National Park (52°58'N, 118°04/W) 1030 m, 8-July-1998 (BCS); Redwater Natural Area (53°55'N, 112°57/W), 28-July-1999 (BCS).
Sthenopis argenteomaculatus occurs from Quebec to New England, and westward to Minnesota and Ontario (Strecker 1893, Forbes 1923, Riotte 1992, Handfield 1999). It is also reported from Alberta (Bowman 1951) and Saskatchewan (Hooper 1981), and Ives and Wong (1988) state this species occurs throughout the prairie provinces. However, this species has often been confused with Sthenopis purpurascens (Forbes 1923), and specimens labeled as S. argenteomaculatus in the Bowman collection (UASM) and the NFC are variants of S. purpurascens. Hooper (1981) and Ives and Wong (1988) provide a figure of a specimen identified as S. argenteomaculatus. Comparisons with illustrations of S. argenteomaculatus
Ritland, D. B. 1990. Localized interspecific hybridization
between mimetic Limenitis butterflies (Nymphalidae) in
Florida. J. Lepid. Soc. 44:163-173. Ritland, D. B. & L. P. Brower. In review. A mimicry related cline
in viceroy butterfly (Limenitis archippus) wing coloration:
model-switching from monarchs (Danaus plexippus) to queens
(Danaus gilippus) in the southeastern United States. Holarctic
Lepid. Saunders, D. S. 1982. Insect clocks. 2nd ed. Pergamon Press.,
Ltd. New York, New York. 409 pp.; xvii. Smith, D. S., L. D. Miller, & J. Y. Miller. 1994. The butterflies
of the West Indies and south Florida. Oxford Univ. Press,
Oxford, England. 346 pp. Williams, T. F. & A. P. Platt. 1987. Absence of diapause in a
laboratory strain of the Florida viceroy butterfly. Am. Midi. Nat.
117(2):346-352.
David Flaim and Austin P. Platt, Department of Biological Sciences, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, Maryland 21250.
Beceived for publication 6 February 1997; revised and accepted 8 September 1999.
from eastern North America (Solomon 1995, Handfield 1999) and specimens from Nova Scotia (BCS) reveal that the figures in Hooper (1981) and Ives and Wong (1988) are actually S. purpurascens. Furthermore, the peak flight period of S. argenteomaculatus is in mid- to late June, whereas S. purpurascens has a much later peak, from mid-July to August (Handfield 1999). Hooper (1981) states that in Saskatchewan, "adults [of the Hepialidae] emerge from mid-July to September". Based on this, previous reports of S. argenteomaculatus for Alberta and Saskatchewan should be referred to S. purpurascens.
Sthenopis purpurascens ranges from British Columbia and the Northwest Territories east to Labrador and New York (Grote 1864, Forbes 1923, Prentice 1965, Handfield 1999), and as far south as the White Mountains of Arizona in the west (D. Wagner pers. comm.). In Alberta, this species is most common throughout the boreal mixed wood and aspen parkland ecoregions, and occurs locally in the mountain and prairie regions. The boreal forest localities include a range of habitats; the Cooking Lake site consists of mature trembling aspen (Populus tremuloides) woods, with an understory of beaked hazelnut, Corylus cornuta, and wild red raspberry, Bubus idaeus. The Redwater site is sandy, open jack pine (Pinus banksiana) forest, interspersed with stands of trembling aspen and paper birch (Betula papyrifera). Green alder (Alnus crispa) is the most common understory shrub. The Palisades Research Centre locality is within the montane ecoregion (Strong & Leggat 1992), and consists of dry, open meadows with stands of trembling aspen and lodgepole pine (Pinus contorta). S. pupurascens also occurs in riparian balsam poplar (Populus balsamifera) groves in the mixed grass prairie ecoregion (Finnegan Ferry site); populations here are likely restricted to riparian areas, since the larvae bore in the roots of poplar and aspen, Populus spp. (Prentice 1965, Gross & Syme 1981). It appears that S. purpurascens occurs throughout most of the province where suitable host plants occur.
The light color form (formerly Sthenopis quadriguttatus) occured together with typical S. purpurascens at all 1997 localities, with the exception of Gregoire Lake P.P. The fact that both phenotypes were collected together at several sites suggests that the habitat requirements and phenology of the two phenotypes are very
NOTES ON THE GENUS STHENOPIS (HEPIALIDAE) IN ALBERTA, CANADA
128
Journal of the Lepidopterists' Society
similar, supporting the synonomy of quadriguttatus into purpurascens proposed by Nielsen et al. (1999). Furthermore, the two phenotypes are almost identical in wing pattern, shape and size; only the ground color varies. Similar morphs (with salmon or brown ground color) occur in Hepialus behrensi (Stretch) (D. Wagner pers. comm.) and Gazorycta noviganna (Barnes & Benjamin) (C. Schmidt unpubl. data).
The relative frequency of phenotypes in the specimens examined is unbiased in males (17 "quadriguttatus" ■ 15 "purpurascens"; X2 = 0.125, 0.50 < p < 0.75) but a significantly higher proportion of females exhibited the quadriguttatus phenotype (46:18; X2 = 12.25, p < 0.001). Assuming both phenotypes are equally likely to be attracted to light, it appears that the mechanisms determining phenotype may be sex-linked.
Flight observations. Male and female Sthenopis purpurascens were observed flying at dusk; nightly flight activity was very brief, occurring between 2210 h and 2300 h (Cooking Lake and Red-water), with sunset at 2135 h (MST). Crepuscular flight activity is characteristic of hepialids, including other members of the genus Sthenopis (Winn 1909, McCabe & Wagner 1989, Wagner & Rosovsky 1991). Females displayed a nearly stationary, hovering flight, usually less than one meter above the shrub understory. One female was observed ovipositing between 2245 h and 2300 h, while exhibiting this type of behavior (Redwater site). Eggs were broadcast over vegetation consisting of low, herbaceous plants and scattered aspen saplings and alder shrubs. Although it was difficult to determine the rate at which eggs were dropped, captive females can lay approximately 1.5 eggs per second.
Males were only rarely observed flying, and flight became rapid and erratic when disturbed. Members of the genus Sthenopis are unusual in that males possess long-range sex attractants, whereas this strategy is usually characteristic of female Lepidoptera (Mallet 1984, Wagner & Rosovsky 1991). Two types of courtship behaviour have been observed in Sthenopis: Males of S. thule and S. argenteomaculatus form mating swarms (leks) which females enter to mate (Winn 1909, Covell 1981), and male S. auratus are sessile and call for females, fanning their wings over the scent tufts (McCabe & Wagner 1989). These two mating strategies may be density-dependent, with male lekking behaviour occurring at higher densities (Wagner & Rosovksy 1991). Since our observations of S. purpurascens failed to turn up males exhibiting courtship behavior, it remains unclear which courtship type this species exhibits.
Female S. purpurascens are more likely to be collected, since there is a high female bias in examined specimens (64 9 : 32 6) and sex ratios are unbiased in the Hepialidae (Wagner & Rosovsky 1991). This is likely due to the fact that females have a longer nightly flight period during which oviposition occurs, while males are only active for a brief time period (D. Wagner pers. comm.). In hepialids where females release sex attractants, collections are often male-biased (Wagner & Rosovsky J 991).
Phenology. Data labels of examined specimens range from July 5th to August 14th, and indicate the peak flight occurs during the last two weeks of July. Larvae of S. purpurascens likely take two years to develop (Vallee & Beique 1979); this can result in adults being much more common in alternating years. Out of the 16 years represented by the specimens examined (between 1931 and 1999), only five are even-numbered years; this phenomenon has also been observed in other hepialids (Wagner et al. 1989). It is thought that biennial species remain synchronous through complex interactions with predators and parasitoids, abiotic catastrophes, and plant defense mechanisms (Mikkola & Kononenko 1989, Mikkola 1976, Wipking & Mengelkoch 1994). The odd-year biennialism in S. purpurascens is synchronous with other biennial Lepidoptera species in the west; many of the Yukon species of Boloria (Nymphalidae), Erebia, Oeneis (Satyridae) and Xestia (Noctuidae) have a greater adult abundance in odd-numbered years (Lafontaine & Wood 1997). This odd-year zone extends from Hudson Bay westward to Fennoscandia (Lafontaine & Wood 1997), but it is not known what causes synchrony between such a wide range of taxa.
Further research is needed to determine the courtship and
mating behavior of S. purpurascens, whether or not density-dependent lekking occurs, if there is a pre-dawn flight period, and to verify if both phenotypes interbreed.
We thank David Wagner for useful suggestions and additional information. Dr. George Ball and Danny Shpeley kindly made material in the Strickland Museum collection available, and Greg Pohl provided access to the collections at the Northern Forestry Centre.
Literature Cited
Bowman, K. 1951. Annotated list of the Lepidoptera of Alberta.
Can. J. Zool. 29:121-165. Covell, C. V. Jr. 1981. A field guide to the moths of eastern North
America. Houghton Mifflin. Boston. 496 pp. Davis, D. R. 1983. Hepialidae. In Hodges, R.W et al. (eds.), 1983.
Check list of the Lepidoptera of America north of Mexico. E.
W Classey Ltd., London. 284 pp. Forbes, W T. M. 1923. The Lepidoptera of New York and
neighboring states. Pt. 1. Cornell Univ. Agric. Expt. Sta. Mem.
68, 729 pp. GROSS, H. L. & P. D. Syme. 1981. Damage to aspen regeneration
in northern Ontario by the ghost moth, Sthenopis
quadriguttatus (Grote). Canadian Forestry Service, Research
Notes 1:30-31. Grote, A. R. 1864. Descriptions of North American Lepidoptera.
Proc. Entomol. Soc. Philadelphia 3:73-92. Handfield, L. 1999. Le guide des papillons du Quebec. Version
populaire. Broquet. Ottawa. 536 pp. + 123 plates. Hooper, R. R. 1981. Saskatchewan ghost moths. Blue Jay
39:141-142. Ives, W G. H. & H. R. Wong. 1988. Tree and shrub insects of the
prairie provinces. Canadian Forestry Service, Northern
Forestry Centre. Edmonton, Alberta. Information Report
NOR-X-292. Lafontaine, J. D. & D. M. Wood. 1997. Butterflies and moths of
the Yukon. In H. V. Danks & J. A. Downes (eds.), Insects of the
Yukon. Biological Survey of Canada (Terrestrial Arthropods),
Ottawa. 1034 pp. Mallet, J. 1984. Sex roles in the ghost moth Hepialus humuli (L.)
and a review of mating in the Hepialidae (Lepidoptera). Zool. J.
Linn. Soc. 79:67-82. McCabe, T. L. & D. L. Wagner. 1989. The biology of Sthenopis
auratus (Grote) (Lepidoptera: Hepialidae). J. New York
Entomol. Soc. 97:1-10. Mikkola, K. 1976. Alternate-year flight of northern Xestia species
(Lepidoptera, Noctuidae) and its adaptive significance. Annales
entomologici Fennici 42:191-199. Mikkola, K. & V. S. Kononenko. 1989. Flight year of the
alternate-year Xestia moths (Lepidoptera, Noctuidae) in northeastern Siberia—a character from the Ice Ages? Nota Lepid.
12:144-152. Nielsen, E. S., G. S. Robinson & D. L. Wagner. 1999. Ghost-moths of the world: a global inventory and bibliography of the
Exoporia (Mnesarchaeoidea and Hepialoidea) (Lepidoptera). J.
Nat. History. In press. Prentice, R. M. 1965. Forest Lepidoptera of Canada recorded by
the Forest Insect Survey. Vol. 4: Microlepidoptera. Canada
Dept. of Forestry, Forest Entomology and Pathology Branch.
Ottawa. 296 pp. Riotte, J. C. E. 1992. Annotated list of Ontario Lepidoptera.
Royal Ontaria Museum, Publications in Life Sciences, Misc.
Publ. Toronto. 208 pp. Solomon, J. D. 1995. Guide to insect borers of North American
broadleaf trees and shrubs. U.S. Dept. Agric, Forest Service.
Agric. Handbk. 706. Washington, DC. 735 pp. Strecker, H. 1893. Descriptions of two new species of North
American Bombycidae. Proc. Acad. Nat. Sci. Philadelphia
45:282-284. Strong, W & K. R. Leggat. 1992. Ecoregions of Alberta. Alberta
Forestry Lands and Wildlife, Edmonton, Alberta. 59 pp.
Volume 53, Number 3
129
Vallee, G. & R. Beique. 1979. Degats d'une hepiale et susceptibilite des peupliers. Phytoprotection 60:23-30.
Wagner, D. L. & J. Rosovsky 1991. Mating systems in primitive Lepidoptera, with emphasis on the reproductive behaviour of Korscheltellus gracilis (Hepialidae). ZooJ. J. Linn. Soc. 102:277-303.
Wagner, D. L., D. R. Tobi, B. L. Parker, W. E. Wallner & J. G. Leonard. 1989. Immature stages and natural enemies of Korscheltellus gracilis (Lepidoptera: Hepialidae). Ann. Entomol. Soc. Am. 82:717-724.
Winn, A. F. 1909. The Hepialidae, or Ghost-moths. Can. Entomol. 41:189-193.
Wipking, W & C. Mengelkoch. 1994. Control of alternate-year flight activities in high-alpine Ringlet butterflies (Erebia,
Journal of the Lepidopterists' Society 53(3), 1999, 129-130
Additional key words: light traps, island colonization.
The arrival and establishment of a species on an isolated oceanic island is a relatively rare event. The likelihood of colonization depends on a variety of features of the species, including dispersal ability, availability of food (hostplants or prey) and ability to reproduce. In this note, I discuss two recent Galapagos records of tropical moths in the context of island colonization.
Thysania zenobia (Cramer) is a tropical migratory species which has been occasionally collected in the Holarctic region (Ferguson et al. 1991). Its life history is unknown, but legumes are considered probable larval foodplants (Covel] 1984). Between 20 and 25 April 1996, three fresh males were collected in a Mercury vapor light trap near Asilo de la Paz, Floreana Island, at 338 m elevation. The trap was located at the border of the agricultural zone and native forest. In March 1997, I collected another specimen in a forest of the endemic composite, Scalesia pedunculata Hook at Los Gemelos, Santa Cruz island, at 580 m elevation, feeding in a bait trap (mixture of rotting fruit). The fresh condition of these specimens suggested that they were from a population extant on the island, rather than migrant. These Galapagos specimens are identical in wing pattern and size to series from continental United States reported by Covell (1984).
Cocytius antaeus (Drury) is one of the larger hawk-moths of the Neotropical region. Members of the Annonaceae have been reported as hostplants (Kimball 1965). Dyar (1901) and Matteson (1933) described its life cycle. I collected two specimens on Santa Cruz Island. On 26 May 1996, I captured a fresh female in a mercury vapor lamp trap at Media Luna (580 m elevation), the fresh condition again suggesting an existing population. This habitat is a mature forest of the endemic Miconia robinsoniana Cong. (Melastomataceae), native ferns and the introduced tree Cinchona succirubra Klotzsch (Rubiaceae). One month later, one worn male was collected by Godfrey Merlen at an outdoor fluorescent light at the Charles Darwin Research Station (sea level).
Although I have never collected larvae of this species, farmers in Santa Cruz and San Cristobal Islands have reported the presence of "voracious green hornworms" feeding on leaves and branches of the introduced custard apple (Annona cherimola Mill). It is likely that these reports refer to C. antaeus, because no other Galapagos sphingids feed on members of the Annonaceae.
The lack of specimens of these two moth species in previous lepidopteran surveys of the islands suggests that these are relatively recent additions to the fauna. Hayes (1975) did not report their presence in the archipelago but his species list was based on specimens collected by early expeditions with less efficient light traps
Satyridae) and Burnet moths (Zygaena, Zygaenidae) from temperate environments. In H.V Danks (ed.), Insect life-cycle polymorphism. Theory, evolution and ecological consequences for seasonality and diapause control. Kluwer Academic Publishers, Dordrecht, Netherlands. 378 pp.
B. Christian Schmidt, 208 - 10422 78 Ave., Edmonton, Alberta, CANADA T6E 1P2, David D. Lawrie, 301 - 10556 84 Ave., Edmonton, Alberta, CANADA T6E 2H4.
Received for publication 5 April 1999; revised and accepted 9 December 1999.
(kerosene lamps) and collections made by amateur entomologists. Recently (1989 and 1992), Bernard Landry carried out an intensive Lepidoptera survey on the islands but he never collected the species (Landry pers. comm.). However, it is also possible that the absence of these species from earlier collections is due to flight time. I trapped both species late at night (2300 h to 2400 h) and few collections have been made during these hours by earlier collectors.
Several features of the biology of these two species may have contributed to their ability to reach the Galapagos. Both, C. antaeus and T zenobia have a history of long dispersal events by active flying to new areas, including oceanic islands (Ferguson et al. 1991, Schreiber 1978). The occurrence of many species of Annonaceae, all of which were introduced by humans in the present century (Lawesson et al. 1987), has probably favored the establishment of C. antaeus.
Although the hostplant of T. zenobia is unknown legumes are a likely candidate (Covell 1984). There are many species of legumes on the Galapagos islands, including native and endemic species, and one of these could provide a suitable hostplant.
I suggest that many of the macrolepidoptera that have colonized the Galapagos arrived by natural means and not as a direct result of human activity. However, their establishment has been facilitated by the increase in the number of introduced plant species, deforestation and other human-related activities.
Voucher specimens have been deposited in the entomological collection of the Charles Darwin Research Station Museum on Isla Santa Cruz, Galapagos.
Acknowledgments
I thank Bernard Landry, Charles V. Covell, Charlotte Causton, Alan Tye and Robert Bensted-Smith for their helpful comments. Valentina Cruz offered her valuable companionship and help in the field. Field work was supported by UNESCO in the project "Ecological monitoring in the Galapagos".
Literature Cited
Covell, C. V. 1984. A field guide to moths of Eastern North America. Hougton Mifflin Co., Boston. 496 pp.
Dyar, H. G. 1901. Life histories of some North American moths. Proc. U.S. Natl. Mus. 23:255-284.
Ferguson, D. C, D. J. Hilburn & B. Wright. 1991. The Lepidoptera of Bermuda: their food plants, biogeography, and means of dispersal. Mem. Ent. Soc. Canada 158. 105 pp.
TWO LARGE TROPICAL MOTHS (THYSANIA ZENOBIA (NOCTUIDAE) AND COCYTIUS ANTAEUS (SPHINGIDAE)) COLONIZE THE GALAPAGOS ISLANDS