CANKER WORMS. 

 W. M. MuNsox. 



Every year come complaints of the defoliation of orchard 

 and shade trees in May and early June. This trouble is usually 

 caused by small slender inch worms or measuring worms which 

 from their effect upon the foliage are commonly called ''canker 

 worms.'' These larvae appear in immense numbers just as the 

 leaves put forth in the spring. They are so small in the begin- 

 ning, however, that they are often overlooked and the cause of 

 the backward appearance of the trees is not recognized. A\'hen 

 tkey first appear, and while not more than one-eighth to one- 

 fourth of an inch long, the larvae gnaw small holes in the young 

 leaves.. As they increase in size the entire leaf, except some of 

 the larger veins, is destroyed and the trees if badly attacked look 

 as if swept by fire. 



Two distinct species of insects are concerned in this destruc- 

 tive work, viz., the fall canker-worm and the spring canker- 

 worm. The habits of the two insects are much alike and to the 

 casual observer there are no distinguishing marks. The striping 

 of the larvae is slightly different, however, and the spring canker- 

 worm has three pairs of legs under the rear portion of its body 

 while the other has but two. Both species are natives of this 

 country and are about equally destructive where they occur. 

 The spring canker-worm is. however, the more widely distrib- 

 uted, ranging from Maine to Iowa and southward to Texas. 



THE SPRING CANKER-WORM (Palcacrita 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. 



