INJURING THE LEAVES. 14$ 



of the defoliated twigs where they have been at work. 

 They are gregarious in habit, and at the times of 

 moulting, or casting of the skin, they migrate in a 

 body to the trunk of the tree, frequently descending; 

 nearly to its base, and, piling themselves one upon' 

 another, remain in a solid mass until the process is: 

 completed. Then they crawl back to the twigs and 

 begin feeding again. When fully grown as caterpil- 

 lars, they go to the ground and change to the pupa 

 state, j\ist beneath the soil surface. Here they re- 

 main until early the following summer, when they 

 emerge as moths to lay eggs for another brood. 



A fair idea of the appearance of the Walnut Cat- 

 erpillar and its moth may be obtained from Fig. 71, 

 which represents a closely-related insect — the Yellow- 

 necked Apple-tree Caterpillar. When at rest or 

 alarmed the larva' assume the peculiar position rep- 

 resented at a. These caterpillars are preyed upon by 

 certain birds, notably the Blue Jay and Red-headed 

 Woodpecker, and by various species of insect parasites. 



Remedies. — These defoliators may be destroyed 

 by spraying tljeir food plants with Paris green or 

 London purple, or the larva) may be crushed when 

 gathered into heaps on the trunk at moulting time. 



The Woolly Maple Bark-louse. 



Pulvinaria innumerabilis. 

 The presence of this insect is manifested in the 

 spring and early summer by the occurrence upon 

 the twigs of maple trees, especially on the under side, 



