PLANTING AND CARE OF TREES 



157 



caterpillars commence feeding on the upper surface of the leaves. 

 A little later, using leaves and silken threads, they build large nests 

 at the ends of the branches, and as cold weather approaches the 

 undeveloped caterpillars enter these nests where they spend the win- 

 ter. From two to three hundred enter the same nest. They come 

 out in April, feed upon the buds and leaves, finish their growth and 

 about the end of June become pupae. They remain in this con- 

 dition for about two weeks, when the adult moths appear. The cat- 

 erpillars when they appear are about one and a half inches in 

 length and are abundantly clothed with hairs which often become 

 broken and fill the atmosphere with fragments. These hairs com- 

 ing into contact with the human skin cause a serious irritation. 



This pest may be controlled by collecting and destroying the 

 winter nests, and this is probably the most satisfactory method. 

 Long-handled "toppers" (fig. 49) may be used for this purpose. 

 Spraying early in May with arsenate of lead, 10 pounds to 100 

 gallons of water, may also be depended upon to keep the insect 

 under control. 



Canker Worms — These are the familiar measuring worms or 

 loopers. They are often observed hanging from a tree by a slender 



Fig. 79. Adult Female Canker- 

 Worm depositing her eggs. 



thread. There are two closely related species, the fall canker worm 

 and the spring canker worm. They feed upon many kinds of trees, 

 but seem to prefer the Apple, Pear, Chestnut, Elm, Hickory, Box 



