THE CANADIAN ENTOMOLOGIST. 209 



NOTE ON LARVAL VARLATION. 



BY A. R. GROTE, 



Director of the Museum, Buffalo Society Natural Sciences. 



In a paper on the Noctuidae of North America (6th Ann. Rep. Peabody 

 Acad. Sci.) I have stated that we should rather expect the acquirements 

 of fresh character to be more apparent during the period of growth of the 

 Lepidoptera. I have elsewhere (Bull. Buff. Soc, i, 130) shown that 

 there is proof in the excessive variation in the larvse of a genus where the 

 adults of the species are remarkably uniform in color and ornamentation, 

 that the larva submits to independent and wide modification from the 

 circumstances of its environment. Under this head I have suggested that 

 all the cases in the Noctuidae where the larvae are very different and the 

 imagos very similar of any two forms distinguished by geographical dis- 

 tribution (e. g., Apatela psi from Europe and Apatela occidetitalis from 

 America) may be ranked. And here the numerous cases cited by Guene^ 

 from Abbot's drawings of the larva must probably be included. The case 

 of these " representative " species is especially interesting and will receive 

 in time a more thorough working out when we come to know the imma- 

 ture forms of more of our species. 



In this first phase of larval variation we have the difference associated 

 with a separate habitat. 



In the next phase we have what Mr. Walsh calls a phytophagic v2ixhi\on 

 of the larva. He has shown such to exist with Hal. tessellaris, and Mr. 

 Hy. Edwards has shown it with regard to the Calit'ornian H. Agassizii. 



Mr. "Walsh's observations on Sphingicampa distigma and Anisoia 

 bicolor I have discussed some years ago, giving good reason to show that 

 an error happened in the matter ; the larva of his " bicolor'^ ( ^ imagos) 

 not having in reality produced the perfect insects with which he associated 

 them. Hence the " generic " differences in the larvse associated with 

 " specific " identity in the imagos in this case assumed by Mr. Walsh do 

 not in reality exist. But the phytophagic variation in Halesidota is not 

 associated with a difference of habitat ; and Mr. Walsh ascribes it to the 

 food plant as the determining condition of the larval environment inducing 

 the variation. The imagos cannot be distinguished. 



