496 ENTOMOLOGICAL SOCIETY 



dent from the specimens which I exhibit before you. The habi 

 tats of the species are different. Alypia octomaculata occupies 

 the Atlantic States from New York to Texas, and, living upon 

 the grape and woodbine, is frequently common in our large 

 cities. In fact, it is far commoner in such places than in the 

 country districts. Alypia langtonii is found in northern New 

 York, the mountains of New Hampshire, Canada to the Pacific 

 Coast, and the mountains of California. It lives on the fireweed 

 and is a wild species, found mostly in the woods remote from habi 

 tations. If the habitats of the two species overlap, it is not so to 

 any marked extent. The female of Alypia langtonii differs ob 

 viously from that of Alypia octomaculata in lacking the basal 

 spot of the hind wings completely or nearly so. In octomacu 

 lata the basal spot is constant, the outer spot occasionally disap 

 pearing. The males of the two species are alike in markings. 

 It has been suggested to me that this was a good case to resort to 

 the male genitalia, the expectation being that these organs would 

 show marked differences. Such, however, is not the case, as the 

 accompanying slides and drawings show. 



The correlation of these species suggests the following ques 

 tions : 



1 . Why should two species, obviously distinct, show no' marked 

 differences in the male genitalia when others are separable prac 

 tically only by this character? 



2. What are the causes determining the choice of food plants 

 in two closely allied species, recently diverged from a common 

 stock? In this case the woodbine and fireweed seem to be more 

 nearly related in some way than their botanical affinities would 

 indicate. It happens that two other closely allied species, Eu- 

 dryas grata and Eudryas unio have selected these same plants 

 as their respective foods. 



In briefly discussing the paper Di. Gill remarked that the simi 

 larity in the males and differences in the females noted in this 

 species is entirely opposed to the rule which holds in birds where 

 the females resemble each other and the males possess the sharp 

 est differentiating characters. 



Dr. Dyar said that the instance was unusual in insects, the 

 males as a rule being more distinct than the females. 



DECEMBER 6, 1900. 



The i56th regular and annual meeting of the Entomologi 

 cal Society of Washington, was held at the residence of Dr. L. O. 



