THE LEPIDOPTERA 



253 



The food plants of the insects in this family are very numerous. 

 Trees and shrubs of many kinds including fruit trees, currant and goose- 

 berry bushes, cranberries and other plants of value to man, suffer from 

 the attacks of these insects, though few are regularly injured, the pests 

 in most cases being destructive only for a year or two, then disappearing, 

 at least for the most part, during quite a period. 



Canker Worms. There are two species of Geometers which are 

 widely distributed over this country and which at times do serious damage 

 to fruit and shade trees. They are known as Canker Worms, and while 

 they differ in certain features, have much in common. In both species 

 the pupal stage is passed in the ground: in both, the female is wingless: 

 in both, the eggs are laid on the twigs of the trees, and in both the cater- 

 pillars feed at about the same time in the spring. 



The Fall Canker Worm (Alsophila pometaria Harr.) occurs in nearly 

 all parts of the Northern United States as far west as Wisconsin, and 

 south at least through the Middle Atlantic States. It has also been re- 



FIG. 253. FIG. 254. 



FIG. 253. Male Fall Canker Worm (Alsophila pometaria Harr.), about natural size. 

 (From Britton, Eighth Rept. Ent. Conn. Agr. Exp. Sta. 1908.) 



FIG. 254. Adult Female Fall Canker Worm on a cluster of eggs. About 2^2 times 

 natural size. (From Houser, Ohio Agr. Exp. Sta. Bull. 332.) 



ported from Colorado and California. The adult male moth (Fig. 253) 

 spreads about an inch and a quarter, its wings light gray with faint 

 markings. The female (Fig. 254) is light gray, and wingless. The 

 moths usually appear late in the fall, escaping from their pupae in the 

 ground, and the females crawl up the tree trunks to the twigs where they 

 lay their eggs (Fig. 254) in clusters. These eggs hatch the following 

 spring, as the leaves develop, and the caterpillars (Fig. 255) feed on the 

 foliage until full-grown some time in June in the Northern States, and 

 earlier farther south. During this time they often drop from the leaves 



