THE CANADIAN ENTOMOLOGIST. 213 



ON THE GEOGRAPHICAL DISTRIBUTION OF NORTH 

 AMERICAN LEPIDOPTERA. 



BY AUG. R. GROTE, A. M. 

 (Continued.) 



Again, the genera Citheronia and Eacles are a South American 

 element in our fauna, while the typical Attacinae, such as Actias, probably 

 belong to the Old World element in our fauna, together with all our 

 Platypterygince. Among the Hawk Moths the genera Fhilampelus and 

 Phlegethontius are of probable South American extraction, though repre- 

 sented now by certain strictly North American species. Mr. Robert 

 Bunker, writing from Rochester, N. Y., records the fact that Philarnpelus 

 Pandorus, going into chrysalis August i, came out Sept. lo as a moth, 

 showing that in a warmer climate the species would become double- 

 brooded. And this is undoubtedly the case with many species the farther 

 we go South, where insect activities are not interrupted so long and so 

 strictly by the cold of winter. Since the continuance of the pupal con- 

 dition is influenced by cold, a diminishing seasonal temperature for ages 

 may have originally affected, if not induced, the transformations of insects 

 as a whole. Butterflies and Moths which are single brooded in the North 

 become double brooded in the South. The winter is the season during 

 which the activities of insects cease and the existence of Lepidoptera 

 becomes artificially lengthened by the intervening of the cold. Prema- 

 ture hibernation is a relic of the time when the winters were longer than 

 at present ; this habit is seen in the case of the larvae of several species 

 of Butterflies, and is otherwise inexplicable. Again, the Notodontid 

 genus Apatelodes is of a Southern type of this Sub-family of the Spinners, 

 while Datana is descended ultimately from Tertiary Arctic forms. In 

 these two cases the genera have probably gradually become distinct from 

 their allies ; nevertheless the relationship to existing genera in South 

 America and Europe may be plainly traced. The foreign elements in our 

 Moth-fauna overlap those which may be considered North American 

 per se. 



From studies of this nature, here briefly summarized and but partially 

 displayed, the Science of Entomology derives an importance not discern- 

 able when it is limited to a mere sorting of species classified after their 

 variety and their value according to the collection. It is part of the task 



