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ON THE GEOGRAPHICAL DISTRIBUTION OF NORTH AMERICAN LEPIDOPTERA

Published online by Cambridge University Press:  31 May 2012

Extract

The following tables contain a partial resumé of the species common to Europe and North America, and also of what are technically known as representative species. I have intended to include only species which I have myself examined and which are with some certainty accurately compared. But the term “representative” species is in itself perfectly elastic, as I have elsewhere shown; in the present case the species compared are believed to have had a common ancestor in the Tertiary. With regard to the introduced species no historical data are accessible to me, and I doubt if any exist; it is a case for the operation of reasonable surmise. I think these tables are of preliminary interest and value; I first commenced to publish similar observations in the Bulletin of the Buffalo Society of Natural Sciences. In a comparison of European and American species we are chiefly indebted to M. Gueneè and Dr. Speyer.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1886

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References

* Of this species I have described the large, pale greenish form, apparently not found in Europe, as H. Umbrosus; the dirty ochrey typical form is apparently common to both hemispheres. But the species of Heliothis may have been introduced by commerce, and I do not refer to them here any further on this account.

This species (= marginata Fabr.) is the same apparently on both continents, but some authors erroneously regard angulata as a form of it. Now the varieties of a species seem always to follow the type form, and as angulata does not occur in Europe, it is not likely that it is a variety of umbra. I have figured both forms in the Buffalo Bulletin, while Dr. Speyer has been at some pains to point out the differences between the two, although his material from America of angulata was incorrectly named for him “exprimens.” Surely Dr. Speyer must be good authority that in Europe no variety of umbra corresponding to angulata exists! That another species of Pyrrhia exists in America is proved by stilla, which is perfectly and undoubtedly a distinct species from any of the others, and handsomer in colors.

* I incline to believe in the possibility that the species of Heliothis and Pyrrhia umbra have been imported by commerce; in this case the other two American species of Pyrrhia may be held as descended from a common ancestor in the Tertiary. This is at the best conjecture, But I am tolerably confident that our two species, angulata and stilla, are perfectly valid and distinct.

This species is regarded as distinct and representative by some writers, but I cannot agree with them; the lateral abdominal tufts are the remarkable specific feature common to both forms; the larva feeds on cabbage, and I think it has been brought over like the Cabbage Butterfly. The Heliothians may have been brought with plants, but I do not feel confident of this with regard to dipsaceus and armiger; it is more likely, perhaps, with regard to scutosus, the larva of which feeds in Europe on Artemisia campestris. Probably specimens of the European Zeuzera Aesculi have occurred in New York, brought by the importation of trees or in wood, but the species has not spread. The Clear-wings above noted have probably been imported, There is a purposed importation of European insects, with a view to acclimatization, going on, conducted by collectors acting from unscientific motives. Prof. Fernald has given us a very careful paper on Tinea and Tineola.

* This category may be in so far almost indefinitely extended since I have shown that all grades of similarity exist, from undoubtedly different, but congeneric, to undoubtedly identical species. I have only included forms which run very close, about some of which perhaps naturalists are not clear whether they are the same or different. In the discussion of these it is to be regretted that much unscientific temper has been displayed, but that is the fault of that amateurism which Dr. Packard so deprecates.

These are probably identical species.

* These are mere selections from a host of species which belong by descent to the North American fauna per se.

This list is also extremely partial; at some time in the past there has probably commenced a movement from South to North which resulted in the settlement of the ancestors of these forms within the territory of North America.