Descriptions of New Noctuce, etc. 303 



ment of any part of the body during any particular period 

 of the twenty-four hours, the causes for its variation may be 

 sought outside of climatic influences to some extent. They 

 will evidently bear more heavily upon the moth, which never 

 or rarely voluntarily exposes the under surface of the body 

 and wings to the light. In the case of Catocala relicta, be- 

 fore cited, I have been struck with the fact that the color of 

 the upper surface of the primaries, which are alone exposed 

 while the moth is at rest in the daytime, does not assist so 

 well in its concealment from enemies as the hue of the same 

 parts in the European species. 



With regard to the "phytophagic species," first observed 

 by Mr. Walsh and afterwards by Prof. Riley, I still think 

 that they should not be necessarily considered as "species in 

 process of formation," although it may be convenient to 

 give them different Latin designations. Some of these cases, 

 such as that of Tortrix Riley ana, Grote, may rest on an 

 error of observation. Both Prof. Zeller and myself believe 

 that the ordinary male of this species is mistaken for a phy- 

 tophagic variety by Prof. Riley. I have formerly shown 

 Mr. Walsh's mistake with regard to Sphingicampa distigma, 

 which he regarded as a different insect, generically and spe- 

 cifically, from Dryocampa bicolor, on the strength of observa- 

 tions in breeding the insect, in which he was apparently de- 

 ceived. These "phytophagic variations" may not go further 

 than they do now, and the forms may continue to interbreed, 

 or finally displace each other. 



Very much more careful observations are needed to draw 

 conclusions as to the relation of the larval state to its food. 

 A separation of the determining cause of variations needs 

 tact, as well as a knowledge of the facts. 



In conclusion, I think that these representative species, 

 studied in all their stages, will throw a strong light upon the 

 horde of forms of these insects with which we are ensra«-ed. 

 I shall be glad if my observations and deductions merely 

 serve to draw fresh attention to the subject. 



