THE TRIBE OF THE ANGLE-WINGS 173 



first named — willow, poplar, and elm — are to be regarded 

 as exceptional cases, and that the normal food of the 

 species is the foliage of a plant belonging to one of these 

 three genera. 



It has generally been supposed that this species is 

 double-brooded in central and southern New England, 

 the butterflies of the first brood appearing early in July. 

 These are said to deposit eggs which hatch into caterpillars 

 that mature into butterflies early in September. These 

 butterflies live through the winter, laying eggs the follow- 

 ing spring. 



It is very probable that as far north as southern New 

 Hampshire the species is commonly single-brooded. 

 During one season when the caterpillars were unusually 

 abundant, a very careful watch was kept for the second 

 brood in New Hampshire and Vermont by several com- 

 petent observers. Only one colony of caterpillars was 

 found and this was at Durham in the southern part of New 

 Hampshire near the seacoast. Consequently, it seems safe 

 to conclude that in northern and central New England, at 

 least, a single brood is the rule rather than the exception. 

 This involves the conclusion that the butterflies seen upon 

 the wing early in autumn are the same ones that de- 

 veloped in July, and that these same butterflies remain 

 alive through the winter and until, in the following May, 

 they lay their eggs. Thus there is a period of ten months 

 of existence in the butterfly state, an extraordinary length 

 of time for a butterfly to live. 



To a large extent the butterflies disappear in August, 

 and the question arises as to what becomes of them. Our 

 observations lead to the conclusion that they go into sum- 

 mer quarters similar to those which they seek out for 



