MAINE AGRICULTURAL EXPERIMENT STATION. I9IO. 339 



b. INSECTS FEEDING FREELY UPON THE LEAVES 

 WITHOUT A NEST AND NOT CONCEALED 

 WITHIN LEAF OR BUD. 



I. Canker Worms. 



I. SPRING CANKER-WORM. 



(Paleacrita vernata.) 



The male moths of this species have rather large, thin, silky- 

 wings, about one inch across when spread. The general color 

 is bluish gray. A well defined row or band of light markings 

 near the outer margin of the front wings, and three darker, 

 irregular bands, across the same wings, together with the 

 slightly l^'ghter color and absence of markings on the hind 

 wings, are characteristic features. The inconspicuous female 

 moths are wingless and, because of this fact, the spread of the 

 species is very slow, occurring mainly by the transportation of 

 nursery stock infested with eggs. 



The moths usually emerge from the ground early in the 

 spring — about April, or farther south, in March — and the fe- 

 males climb up the trunks of trees to deposit eggs. The eggs, 

 which are shaped something like hens' eggs and are about the 

 size of fly specks, are deposited in irregular masses, usually 

 partially concealed by loose pieces of bark. They hatch about 

 the time the leaves unfold; the time varying with the locality 

 and the season. The larvae are "measuring worms" with 2 

 pairs of legs at the hind end of body (fig. 5). The young 



Fig. 5. a, larva, showing the two pairs of pos- 

 terior legs ; b, single egg, much enlarged. (After 

 Riley). 



larv^ are voracious feeders and they grow rapidly, usually 

 attaining full size in from three to four weeks from the time of 

 hatching. Upon reaching full size they drop to the ground, 

 burrowing beneath the surface to a depth of two to five inches. 

 Here each one forms a cell, lined with silk which it spins, and 

 soon transforms to the chrysalis stage, where it remains until 

 the following spring, when the adult moth emerges as before. 



