730 



AN INTRODUCTION TO ENTOMOLOGY 



The larvae leave the nest daily in order to feed; and spin a sill-zen 

 thread wherever they go. The larvEe become full grown early in 

 June; one of them is represented on a partially-eaten leaf in the 

 figure. When ready to transform they leave the trees and make their 

 cocoons in some sheltered place. These cocoons are quite peculiar 

 in appearance, having a yellowish white powder mixed with the silk. 

 The pupa state lasts about three weeks. The easiest way to fight 

 this pest is to destroy the webs containing the larvae as soon as they 

 appear in the spring. This should be done early in the morning, or 

 late in the afternoon, or on a cold day, when the larvae are not scattered 

 over the tree feeding. 



Fig. 934. — Malacosma americana, eggs, tent, larva, cocoons, and adult. 



Another species of the genus Malacosdnia found in the East is the 

 so-called forest tent-caterpillar, Malacosdnia dtsstria. The range of 

 this species extends throughout the United States and Canada. It 

 differs from the preceding species in that the larvas do not construct 

 a true tent. It feeds on the leaves of many forest and fruit trees, but 

 maple is its favorite food-plant. In other respects its life history is 

 quite similar to that of the apple-tree tent-caterpillar. The moth 

 differs from M. americana in having the oblique lines on the wings 

 dark instead of light ; the larva differs in having a row of spots along 

 the back instead of a continuous narrow line; the egg-masses differ 



