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Volume 29, Number 1
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----------, & D. W. Kaufman. 1973. Genie variability and strategies of adaptation
in animals. Proc. Nat. Acad. Sci. USA 70: 1875-1877.
----------, M. H. Smith, S. Y. Yang, W. E. Johnson, & J. B. Gentry. 1971. Biochemical polymorphism and systematics in the genus Peromyscus. I. Variation in the old-field mouse (Peromyscus polionotus). Studies in Genetics VI. Univ. Texas Publ. 7103.
Sokal, R. R., & F. J. Rohlf. 1969. Biometry: The Principles and Practice of Statistics in Biological Research. W. H. Freeman & Co., San Francisco. 776 p.
A SECOND EXTANT COLONY OF PIERIS VIRGINIENSIS IN ONTARIO (PIERIDAE)
The relatively recent acceptance of Pieris virginiensis Edwards as a species (distinct from Pieris oleracea) leads to considerable difficulty in determining its range from existing collections. Local and colonial in its distribution and at the northern limit of its range in Ontario, where it inhabited only certain selected rich hardwoods of the many where Dentaria spp. grows, it had been considered extinct in the province. Its previously known stations, cited by Riotte (1967, Proc. Entomol. Soc. Ontario 98: 27-29), at Hamilton, London and Etobicoke, have all succumbed to urban development. However, in 1965 it was rediscovered by Holmes in the Halton County Forest Riotte (1967), and since then this extensive woods has remained the only known Ontario locality despite extensive field work throughout the province.
Unusually interesting, then, was the reported specimen by Warren (1963, Entomol. Ts. 84: 1-4), from "Grand La Cloche Island" (presumably Great Cloche Island, Manitoulin District) in the British Museum, with the implication of a possible surviving colony in that area.
Now, despite examinations of many stations in southern Ontario for the relatively common Dentaria, until 1973 Pieris virginiensis was found only in one. In the heavily glaciated limestone of Manitoulin District even suitable habitat for Dentaria is unusual, namely accumulations of rich soil sufficiently deep to support hardwood forest. To my knowledge, such habitat is absent on Great Cloche Island. Furthermore, even amongst these relatively infrequent hardwood forests, the occurrence of Dentaria is infrequent. Soper (1973, pers. comm.), was able to find only four stations, all of Dentaria diphylla, in the whole district, only one of which was on Manitoulin Island itself. A survey of Manitoulin Island by the author and some members of the Toronto Entomological Society failed to reveal any additional Dentaria in the many possible suitable sites examined until, in May 1972, the author was directed to a badly cut-over maple woods in the central part of the island where moderate numbers of both Dentaria diphijlla and laciniata were in flower. Despite several visits no Pieridae were observed there in 1972. However, on 20 May 1973, four female specimens were taken flying weakly amongst the clearings and along paths in the woods. Identification has been confirmed by J. C. E. Riotte, and two specimens deposited in the collection of the Department of Entomology and Invertebrate Zoology, Royal Ontario Museum.
This collection completes a link in the chain of occurrences of this species between Michigan in the west and southern Ontario and New York to the southeast, raising the hope that still further populations may yet be discovered. Pieris virginiensis, because of its habits and local habitat, which is especially vulnerable to urban development and cutting for firewood, must be regarded as an endangered species in Ontario.
R. R. Tasker, 121 University Wing, Toronto General Hospital, Toronto, Ontario, Canada.