19Q 



PSrCHE. 



[April 1889. 



brown, with coxae blackish, and tarsi 

 together with intermediate and posterior 

 femora, obfuscate. Legs of $ Hghter col- 

 ored, with coxae unicolorous with legs ; 

 posterior tibiae at tip, and posterior tarsi 

 dusky. Tegidae piceous. Wings sub- 

 hyaline ; veins and stigma deep brown. 

 Ovipositor nearly as long as abdomen ; 

 sheaths piceous. 



Described from four specimens (3 9 1 

 I ^) bred from cocoons found in con- 

 nection with Alegilla maculata. 



The cocoon is of a clear reddish 

 brown color, 4 mm. long by 3 mm. 

 wide. Its texture is compact, except 

 that there, is considerable loose silk on 

 the outside. 



COSMOPOLITAN BUTTERFLIES. 



BY SAMUEL HUBBARD SCUDDER, CAMBRIDGE, MASS. 



Strictly speaking, there is no such 

 thing as a cosmopolitan butterfly ; yet 

 there is one species, Vanessa carditis 

 which may well merit that name, since 

 it is found in every quarter of the globe 

 with the exception of the arctic regions, 

 a part of South America and most of the 

 West India islands ; there are also other 

 butterflies whose recent extension natu- 

 rally leads to the inquiry. What should 

 prevent their spreading over the entire 

 globe, or what are the elements that 

 enable a butterfly to gain and maintain 

 a foothold in so many diverse regions. 



Let us look for a moment at the 

 peculiarities of distribution of this nearly 

 cosmopolitan butterfly. It belongs to a 

 subdivision of the genus Vanessa^ the 

 members of which (with the sole excep- 

 tion of this cosmopolitan species) are 

 found exclusively in the New World ; 

 while the antithetical section (with the 

 single exception again of one member 

 found both in Europe and the LTnited 

 States) is exclusively confined to the 

 Old World. Judging from this fact we 



may venture to assert with considerable 

 confidence that this cosmopolitan butter- 

 fly originated in America. Tet it is 

 just on this continent that its distri- 

 bution is most limited ! It is known in 

 only a comparatively small portion of 

 South America and occurs on none of 

 the West India islands, with the excep- 

 tion of Cuba, where it is rare. The 

 cause of this limitation cannot be attri- 

 buted to the food plant of the cater- 

 pillar ; for the thistles upon which it 

 lives are quite as abundant in these 

 i-egions as in many others which it has 

 invaded, certainly sufficiently abundant 

 for all its uses. Nor can the heat of the 

 tropics be placed as a difficulty in the 

 ^vay, since there is no place where it 

 flourishes more abimdantly than in the 

 tropics and subtropics of the Old World, 

 repeated invasions of Europe by hordes 

 from the south where they had out- 

 grown their opportunities being already 

 on record. 



Assuming, then, America to have 

 been its original home, it would seem 



