528 GENERAL BIOLOGY 



herself eat of these trees. Moreover, she discriminates 

 unerringly between living and dead trees. The eggs are 

 placed in cylindric clusters about the tip of a twig, and are 

 covered by a secretion which hardens into an incrustation 

 that incloses the egg-mass, and renders it weather-proof. In 

 spring, hatching occurs just as the first leaves are opening. 

 Doubtless the increasing warmth of the season stimulates the 

 young larvae to come forth. The greater warmth of the pre- 

 ceding season had no such effect because the young were not 

 yet ready. 



The larvae, emerging together from the eggs, begin at once 

 to feed, to spin silken threads, and to establish a common nest. 

 In selecting a site they descend the twigs until they come to a 

 fork of considerable size, often passing by several lesser forks. 

 The larvae will forage above the nest so long as they live in 

 it, and the selection of a large fork as a homesite insures 

 forage overhead for the rearing of a large brood of cater- 

 pillars. Each larva spins a very fine thread of silk wherever 

 it goes attaching it underfoot as it crawls alon over twig or 

 leaf. This line serves as a trail for return to the nest : and 

 if a larva be jostled from the bough, it may hang dangling 

 from its line, and then by reefing it in, may climb up to the 

 bough again. The nest is a compound of such lines, drawn 

 taut across the angle of the fork and built up literally "line 

 upon line, here a little and there a little." There are a few 

 larger openings left along the main lines of travel; but the 

 nest as a whole is so dense and intricate that one may remove 

 both nest and caterpillars from the tree, by winding them 

 together on the point of a stick. 



When the larvae are grown, a "wander-lust" seizes them; 

 they leave the nest and forage more widely. And when 

 ready for transformation to pupae, their behavior is entirely 

 changed. They crawl down the tree, and shun the light and 

 shun each other. Each one crawls into some crevice, or 

 under a heap of leaves and, finding a suitable space, spins 



