756 



AN INTRODUCTION TO ENTOMOLOGY 



Fig. 965. — Etigonia j -album. 



The Compton tortoise, Eugonia j-dlbum. — This butterfly (Fig. 

 965) resembles in its general appearance those of the germs Polygonia, 



but it is sharply distin- 

 guished from them by the 

 inner margin of the fore 

 wings being nearly 

 straight, by the heavier 

 markings of the fore 

 wings, and by the pres- 

 ence of a whitish spot on 

 both fore and hind wings, 

 near the apex, and be- 

 tween two larger black 

 patches. On the lower 

 surface of the hind wings 

 there is a small L-shaped 

 silvery bar. This species 

 occurs throughout Cana- 

 da and the northern portion of the United States east of the Rocky 

 Mountains. It is double-brooded. 



Polygdnia.— The butterflies of this genus resemble the preceding 

 species in having a metallic spot on the lower surface of the hind 

 wings, but differ in having the inner margin of the fore wings roundly 

 notched beyond the middle. 



Ten species occur in this country. These differ principally in the 

 coloring and markings of the under surface of the hind wings. The 

 following are some of the more common ones. 



The green comma, Polygonia faunus. — The silvery mark of the 

 hind wings is usually in the form of a C or a G, the ends being more 

 or less expanded (Fig. 960, 2) but sometimes it is reduced to the form of 

 an L. The lower surface of the wings is more greatly variegated than 

 in any other species of this genus; and there is a larger amount of 

 green on this surface than in any other of the eastern species, there 

 being two nearly complete rows of green spots on the outer third 

 of each wing. 



The larva feeds upon black birch, willow, currant, and wild goose- 

 berry. This is a Canadian species ; but it is also found in the Moun- 

 tains of New England and of New York, and in the northern portions 

 of the Western States, extending as far south as Iowa. It is single- 

 brooded. 



The hop-merchant, Polygonia comma. — As in the preceding species, 

 the silvery mark of the hind wings is in the form of a C or a G (Fig. 

 960, 3) but the general color of the lower surface of the hind wings is 

 very different, being marbled with light and dark brown; and the 

 green spots so characteristic of faunus are represented here by a few 

 lilaceous scales on a submarginal row of black spots. 



Two forms of this species occur. In one, P. comma dryas, the hind 

 wings above are suffused with black on the outer half, so that the 

 submarginal row of fulvous spots is obsured, and on the lower side the 



