THE ENEMIES OF THE CANKER-WORM 



35 



Oo 



There are two distinct 

 species of canker-worms, the 

 fall canker-worm (Anisoft- 

 teryx pometa?'ia) and the 

 spring canker-worm (Pa/ea- 

 crita vernata) . The moths 

 of the former emerge mostly 

 in autumn, while those of 

 the latter appear in spring. 

 The various stages of the 

 spring species are represent- 

 ed in Fig. 2, and of the fall 



i->- a mi Fig. 2. — The spring canker-worm: a, 



species in rig. x. As will , . ' 



egg mass, natural size; /', egg, magni- 

 be seen, the insects resemble fied . f> , arva . ^ female moth; e> ma]e 



each other, one of the chief moth. (After Riley.) 



differences being in the shape 



of the egg (see b in each figure). Both species are found in 



New Hampshire. 



The canker-worm is distributed largely through the action of 

 the wind in blowing suspended larvae from one tree to the vi- 

 cinity of another. Lowell has described the process in these 

 lines : 



" The worm, by trustful instinct led, 



Draws from its womb a slender thread 

 And drops, confiding that the breeze 

 Will waft it to unpastured trees." 



THE ENEMIES OF THE CANKER-WORM 



Fortunately, the canker-worm is beset by enemies from the 

 time the egg is laid until the adult moth dies. There is a 

 tiny parasite which develops in the egg, destroying its con- 

 tents. There are several species of parasites which prey upon 

 the larvae, as well as various predaceous insects which devour 

 it bodily. But perhaps the most effective enemies are the 

 birds ; repeated observations and investigations have shown 

 that nearly all our common birds feed freely on the canker- 

 worm. Apparently, no other injurious insect is taken so 

 freely by a great variety of birds. The observations made in 

 Massachusetts, by Mr. C. E. Bailey, and reported by Mr. E. H. 



