INJURING THE LEAVES. 



139 



the larvse develop, and during later life using bits of 

 twigs or steins in their construction, instead of leaf 

 particles. The full-grown larva is represented in its 

 bag at /', and without it at a. When fully developed 

 the worms descend to the earth by means of silken 

 threads, and crawl about until they reach the bases 

 of other trees, which they ascend. This is the way 

 the species migrates. The larvse pupate within the 

 cases, and about three weeks later change to moths. 



Fig. 69. Bag-worm : a, larva: b, maleptipa; c, female moth : d, male 

 moth ; e, bag and pupa case cut open to show eggs ; /, full-gn iwn 

 larva with bag; g, young larva? with their conical coverings. 



The two sexes of the moths differ greatly, the male 

 (d ) having well developed wings, while the female 

 (c) is wingless. The latter deposits her eggs in the 

 empty pupa case from which she has emerged, and 

 falls to the ground, where soon afterward she dies. 

 The Bag-worm feeds upon a great variety of trees, 

 and apparently prefers coniferous to deciduous sorts. 



