Click here for the original journal page (in Acrobat pdf format).

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.

148

Journal of the Lepidopterists' Society

to a school student, Miss Darcy Berry, who, on realizing the unusual nature of the moth, donated it to the Manitoba Museum of Man and Nature.

The general coloration is dark brown, but with the recognizable markings of A. p. polyphemus. The ventral surface is of the same colour as the dorsum but is contrastingly marked as is typical of specimens from Manitoba (Figs. 2, 4). In wingspan the mounted specimen measures 114 mm and the greatest length of the right front wing is 61 mm.

There are some references to melanistic A. polyphemus in the literature. Holland (1903, The Moth Book. Doubleday, New York. 479 p.) mentioned ". . . one or two fine melanic specimens, in which the wings are almost wholly black on the upper side." Packard (1914, Mem. Natl. Acad. Sci. 12: 207) referred to Holland's specimens and (p. 205) mentioned three purplish coloured specimens reared from cocoons from Macon, Georgia. Ferguson (in Dominick, R. B. et al. 1972, The Moths of America North of Mexico, fasc. 20.2B Bombicoidea (in part)) considered melanistic specimens to be very rare. The authors of the present paper are unaware of any prior published illustration of a melanistic A. polyphemus.

We wish to thank Mr. Richard Westwood, University of Manitoba, Winnipeg, and Mr. C. S. Quelch, Winnipeg, for examining their collections for melanistic specimens.

William B. Preston and Wm. Brian McKillop, Manitoba Museum of Man and Nature, 190 Rupert Avenue, Winnipeg, Manitoba R3B ON2, Canada.

Journal of The Lepidopterists' Society 33(2), 1979, 148-149

BISTON COGNATARIA (GEOMETRIDAE): FREQUENCY OF MELANIC MALES IN TYRINGHAM, MASSACHUSETTS, 1958-1977

Sargent (1974, J. Lepid. Soc. 28: 145-152) reported the frequency of the melanic versus the typical form of the Salt and Pepper Geometer, Biston cognataria (Guenee), in collections totalling 129 specimens (presumably all male) from central Massachusetts for the years 1971-1973. The percent of melanics ranged from zero in 1971 to 5.6 in 1973. The overall incidence for the three years was 6/129 = 4.4 percent. Sargent discussed the question of industrial melanism and urged the continued reporting of data bearing on this problem.

During 18 years of the period from 1958 through 1977 (omitting 1961 and 1962) I examined a total of 833 males of this species taken at light in Tyringham, a rural area in southern Berkshire County of western Massachusetts, elevation 313 meters. Atmospheric pollution in the area was minimal as evidenced by the common presence of lichens on tree trunks. Collections in each year covered a period from late May to mid September or later. The overall incidence of melanism was 83/833 = 9.96 percent. The yearly incidence ranged from zero in six of the 18 years, to a high of 33.3 percent (2/6) in 1971 (Table 1). The average of yearly incidences was 7.31 percent. Abundance of moths available for examination ranged from zero in 1970 to 253 in 1966, in which year the incidence of melanics was 11.1 percent. If any general trend is evident, it is toward a recent diminution in the number of melanics.

Volume 33, Number 2

149

Table 1. Incidence of melanism in males of Biston cognataria in Tyringham, Massachusetts, 1958-1977.

Asher E. Treat, Research Associate, The American Museum of Natural History, New York, New York 10024.

Journal of The Lepidopterists' Society 33(2), 1979, 149-150

NOTES ON THE OCCURRENCE OF ERORA LAETA (LYCAENIDAE) IN MICHIGAN'S WESTERN UPPER PENINSULA

Erora laeta (Edwards) has been known from only one location in the upper Great Lakes region. On 14 May 1955, Edward G. Voss and Warren H. Wagner, Jr. had the good fortune of encountering four individuals of this elusive butterfly, two males and one female of which were captured. These records from Bliss Township, Emmet Co., Michigan represented a first for the state and substantially extended the known range of this exceedingly rare species. In a paper recounting these captures (Voss & Wagner 1956, Lepid. News 10: 18-24), the authors gave considerable attention to the environmental characteristics of the collecting site. In brief, all of the specimens were captured at or near a moist spot, which was fed by a small ground spring situated on the south side of an east-west dirt section road. Botanical-ly, the surrounding area was described as a very young deciduous woods, with American beech (Fagus grandifolia Ehrh.), sugar maple (Acer saccharum Marsh.), basswood (Tilia americana L.), American elm (Ulmus americana L.), white ash (Fraxinus americana L.), and pin cherry (Prunus pensylvanica L.) dominating.