THE MONTHLY BULLETIN. 



185 



Fig. 171. — The spring cankerworm {Palea- 

 (rita vernata Peck), a, adult male; b, fe- 

 male ; c, larva ; d, egg enlarged and in egg- 

 mass. (After Riley.) 



THE SPRING CANKERWORM. 



Paleacrita vernata Peck (Family Geometridse). 



(Figs. 171, 172.) 



General Appearance.— The larva? are dark olive-green, brown or 

 nearly blat-k. vc^ry slender and abont one ineh long. Because of their 

 looping method of traveling they are often called measuring worms. 

 Ill this species they possess 

 but two pairs of legs en the 

 under side of the posterior 

 half of the body. The cocoon 

 is composed of tough silken 

 w^eb. which is not ea.sily 

 broken. The pupa is grayish 

 brown. The female is wing- 

 less and covered with soft 

 gray down. The male is 

 winged and gray in color. The eggs are regularly oval. 



Life History.— The female of the spring cankerworm oviposits in the 

 spring "before the buds of the apple trees start. The eggs are laid 

 singly or in irregular masses in crevices or under the bark-scales on 

 the limbs, trunks, twigs or 

 leaves. The young cankerworms 

 hatch out jvist in time to begin 

 destroying the first young leaves. 

 They often occur in such num- 

 bers as to almost entirely defoli- 

 ate the trees and cause great 

 loss. After they mature they 

 drop to the ground and pupate 

 in a cocoon, just beneath the 

 surface, where they hibernate 

 through the winter, and the 

 adults appear early the next 

 spring. There is but one genera- 

 tion each year. The females, 

 not having wings, must crawl up 

 the trunk in the spring to 

 deposit their eggs in suitable 

 places during March and April. 



Distribution. — Throughout 

 the apple-growing sections of 

 the central part of the State. 



Food Plants. — Apples, apri- 

 cots, cherries, prunes, the foliage 



, •-. ^, IT Fig. 172. — Work of cankerworms on 



being attacked. apricot. (After Craw.) 



Control.— Inasmuch as the female is wingless the spread of this pest 



