55 



wingless, and in botii tlie eggs are laid on the twigs. These facts 

 are of importance for the successful treatment of both pests. 



The fall canker worm moths come out of the ground late in the 

 fall and the female moths crawl up the trunks of trees to the twigs, 

 where they lay their eggs. 



^ r\\il^ 



Fig. 3. Fall canker worm, a, male moth ; b, 

 female moth ; c, d, structural details. 



The eggs do not hatch until 



the following spring, when 



the tiny caterpillars (inch 



worms, measuring worms or 



loopers, as they are variously 



called), begin feeding on the 



newly developed leaves. By 



the middle or end of June feeding has been completed and the cater- 

 pillars, now an inch or more 

 in length, either crawl down 

 or spin down a thread to the 

 ground, which they enter and 

 where they transform to the 

 moths which will appear late 

 in the fall. 



The spring canker worm 

 moths come out of the 

 ground during the first warm 

 spring days, and like the 



others crawl up to the twigs, where they lay their eggs. These soon 



hatch, however, and the 



caterpillars feed during the 



spring at the same time as 



do those of the fall canker 



worm, and also complete 



their feeding at about the i7- , ^ • i 1 *i, 



° Fig. 5. Spring canker worm, a, male moth 



same time. They then enter b, female moth; c, d, e, structural details. 



the ground to transform, but 



do not leave it for the trees the same year, waiting until the follow- 

 ing spring. 



The first year canker worms become so abundant as to be noticea- 

 bly destructive it is probable that the earliest knowledge of this will 

 be obtained from the appearance of the leaves where the caterpillars 

 are at work. In such cases, spraying with arsenate of lead is the 



Fig. 4. Fall canker worm, a, side view of 

 single egg ; b, top view of same ; e, egg mass, 

 natural size ; f, full-grown caterpillar ; c, d, g, h, 

 structural details. 



