282 INSECTS INJURIOUS TO STAPLE CROPS. 



" that not one in ten of the insects ever attains the butter- 

 fly state." 



The chrysalis stage of the second brood is somewhat 

 longer than the first, sometimes lasting twenty-six days, 

 and the butterflies emerge from the latter part of August 

 until the end of October, and at once seek quarters in 

 which to hibernate over winter. 



Both this species and P. comma are dimorj^hic, the 

 winter and summer forms differing in both sexes in both 

 the upper and lower aspects of the wings. In the South, 

 where from three to five broods occur in a season, both 

 +''^rms are usually found in the second and third broods, 

 ^ummer form, var. twibrosa, gradually decreasing 

 all of the fourth brood are the hibernating winter 



^JL, va?'. fahricii. 



The Comma-butterfly {Polygonia comma Harr.). 



The Comma-butterfly is most common throughout the 

 East from New England to North Carolina and Tennessee, 

 though occasionally found as far west as Wisconsin, Iowa, 

 Nebraska, and Texas. 



Its life-history is practically the same as that of the 

 species just described. The larvae of the first brood some- 

 times seriously damage young elm-trees, which have been 

 Ijut recently reset, by eating them bare of the foliage. The 

 winter form hibernates about a month earlier, being rarely 

 seen in October. As a rule a similar dimorphism occurs, 

 the hibernating form being known as var. harrisii and the 

 summer form var. dryas, though the distinction is not 

 as marked in this species. 



The half -grown larva is black, with a yellowish stripe 

 along the side from the third segment, and with yellow 



