INSECTS AND THEIR CONTROL 233 



stage. The larvae are quite variable in color, some of them 

 being green, others brown and still others almost black. 

 They are quite slender and, when full grown, are practically 

 one inch long. 



These canker-worm larvae are very often called measuring 

 worms because of their peculiar looping way of traveling. 

 They have two sets of legs, the forward set being called 

 prolegs. The two species differ in the number of these pro- 

 legs; the spring insect has two pair, while the fall species has 

 three. 



Control is best brought about by the application of arsenate 

 of lead while the larvae are quite small. Nicotine-sulfate 

 has also been used successfully, especially at the time when 

 the larvae are not more than half grown. When they become 

 adult, they may devour large quantities of spray-covered 

 foliage, without being killed. 



The female moths of both species are wingless and herein 

 differ markedly from most other moths. Because of this fact, 

 control has been accomplished by the placing of sticky tangle- 

 foot or some other kind of band around the trunks of trees 

 to prevent the female moths from climbing up to deposit their 



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344. Red-humped caterpillar. Frequently fruit-trees are 

 infested by a larva which is characterized by a red head and 

 red hump bearing black spines. This hump is on the first 

 abdominal segment. The abdomen bears stripes which are 

 also quite 'characteristic of the species. This larva, because of 

 its appearance, is called the red-humped caterpillar. 



The adult of the insect is a brown or grayish moth. It 

 lays its eggs on the leaves of the host plant where they hatch, 

 the larvae afterwards feeding gregariously, that is, in clusters, 

 'he winter season is spent in the pupal stage, the moths 

 issuing from the pupa cases in the spring, to deposit their 

 eggs. 



Control may be brought about by removing the clusters of 



