ii8 



THE FOREST TENT CATERPILLAR 



DESCRIPTION OF THE LIFE STAGES 



Egg. — The egg mass of this Forest Caterpillar is in the form 

 of a belt encircling the smaller twigs of the various food-plants. 

 Its general shape is represented in Fig. 46, the length of the 

 belt varying from one fourth to one half of an inch ; the diame- 

 ter is usually one fourth of an inch. 

 The belt terminates abruptly at each 

 end, although it is not as a rule 

 squared off. The outside of the belt 

 consists of a glistening, varnish-like, 

 brownish or lead-gray material, which 

 covers the eggs. When the eggs are 

 first laid, and for some months after- 

 ward, this covering remains entire, 

 but as the winter passes it becomes 

 more and more broken, so that by 

 spring it generally has a rather rag- 

 ged appearance. By removing the 

 covering the eggs will be found be- 

 neath, resting side by side at right 

 angles to the supporting twig. Each egg is a trifle longer than 

 wide, and is covered with a reticulated network of the same 

 varnish-like material that conceals the mass as a whole; this 

 network serves to attach the eggs to the twig and to each other. 

 The eggs are of a dull gray color, showing white in some places. 

 When the Caterpillars hatd: they gnaw off a circular cap on 

 the upper end of the egg, and come out through the hole 

 thus made. Each egg is about one twentieth of an inch long. 

 The number of eggs in one belt varies from less than 150 to 

 more than 225, the average being nearly 200. When the in- 

 sects are so abundant that there is a partial exhaustion of the 

 food supply of the caterpillars, the' normal number of eggs are 

 not laid, the egg rings being much smaller than usual. 



Larva. — The full-grown Forest Caterpillar is about two inches 

 long and about one fourth of an inch thick. In shape it is 

 cylindrical, with six jointed legs arranged in pairs directly 

 back of the head, eight thick prolegs along the middle, and 



Fig. 46. — Egg Masses. 



