LIFE-HISTORY 



79 



in all directions, utilizing any shelter they may come upon. 

 They commonly crawl up the sides of houses and other build- 

 ings, and form their cocoons along the clapboards or beneath 

 the gables. 



The cocoon is made of silk with an outer mass very loosely 

 spun, and an inner mass so much more closely woven that it 

 forms a web of almost parchment-like texture. As in the case 

 of the American Tent Caterpillar, the threads of the cocoon are 

 white when first spun, but become yellow by being saturated 

 with a liquid which the caterpillar ejects shortly before pupa- 

 tion. As this liquid dries it leaves a yellow powder in the silk. 



Soon after forming the cocoon around itself the caterpillar 

 changes to the pupa or chrysalis condition, becoming an oval 

 brown object without legs or wings, able to move only by a 

 wriggling of its body. In this condition it takes no food, but 

 within the quiet exterior the body of the caterpillar is being 

 developed into that of a moth. 



About ten days after the cocoon was made the pupa skin 

 cracks open, and a brownish moth emerges from the cocoon : 

 this is the adult condition of the Forest Caterpillar. The male 

 moths are slightly smaller than the females, as may be seen 

 from Figs. 23 and 25, the first of which represents the male 

 and the second the female, both natural size. 



The moths generally make their appearance the latter part 

 of June. Soon afterwards the females deposit their eggs in 

 masses of about two hundred each upon the twigs. The 

 moths, having completed the cycle of life, die soon after the 

 eggs are laid. 



The eggs thus deposited early in July are to remain 

 unhatched until the following spring. The actual formation 

 of the tiny caterpillars from the contents of the egg takes place, 

 however, within a few weeks after 

 the}' are laid. The minute but fully- 

 formed caterpillars may be found 

 within the egg shells, by a careful 

 examination, any time between Sep- 

 tember . and the following April. 

 The caterpillars remain during this 

 long period quietly confined within 



"^^&^^\ 



Fig. 23. Male Moth of Forest 

 Tent Caterpillar. Natural 

 size 



