PLANTING AND CARE OF TREES 155 



the trouble and to know something about its feeding habits. Many 

 of the failures in spraying may be attributed to the application of 

 the wrong remedy. Since there are many books and Experiment 

 Station bulletins relating to specific shade tree pests, it is necessary 

 here to describe only the most destructive forms. Every state has 

 its experiment station where insects may be sent for identification 

 and where advice may be obtained regarding the control of insects 

 and diseases and other subjects. In the descriptions that follow no 

 attempt is made at completeness. To call attention to the more 

 striking characters and habits is the object. The character of the 

 injury is emphasized because this is usually the most available 

 means of identification. 



LEAF-EATING INSECTS. 



Bag ^Vorm — ■ This ins,ect gets its name from the fact that the 

 larva carries a sort of bag that protects its body. The forepart 

 of the caterpillar's body projects through the mouth of the bag. 

 These bags are very conspicuous on trees in winter and contain 

 the eggs from which the caterpillars hatch during the month of 

 May. Each young caterpillar immediately after hatching com- 

 mences to build a sack for itself, using small pieces of leaves and 

 fastening them together with threads of silk. The bags increase in 

 size as the insect develops and are from one to two inches in 

 length when the larva is full grown. The larva feeds on a great 

 variety of trees, including the evergreens. Allien the insect is ready 

 to pupate it attaches the bag to a branch or twig and reverses its 

 position in the bag. In about three weeks the mature insect 

 emerges in the form of an inconspicuous moth. The male moth 

 flies' away, but the female moth is wingless and legless and remains 

 in the bag until she has deposited her eggs, when she wriggles out 

 and dies. 



The pest may be controlled by collecting the nests during the 

 winter or by spraying with arsenate of lead as soon as the cater- 

 pillars appear. 



Brown-tail Moth — This pest was introduced into ^lassachusetts 

 about twenty years ago and is now spreading rapidly throughout 

 the neighboring states and Canada. It feeds on a great variety 

 of plants and is especially destructive on the Maples, Elms, and 

 Oaks. The adult moth is snowy-white and is distinguished readily 



