APPLE-TREE CATERPILLAR ITS NEST,' HOW BUILT. 191 



worms poured out of the nest again and commenced eating, vora- 

 ciously. And invariably upon very warm days these caterpillars 

 eat much more ravenously than at other times. Two or three 

 days of hot weather, such as frequently occur about the time of 

 planting corn, give them greedy appetites and cause them to 

 advance rapidly in size. 



The tent or nest, which is always placed in the fork of a limb, 

 is enlarged from time to time, until it becomes from eight inches 

 to a foot in diameter. It is composed of a number of sheets or 

 layers formed of silken threads woven closely together like dense 

 cob-webs. These sheets are placed parallel to each other, and 

 at such distances apart as enable the worms to crawl between 

 them to repose, the spaces being much narrower between the 

 inner layers, formed when the worms were small, than between 

 the outer ones. The nest thus resembles the several sheets, 

 blankets and other coverings upon a bed, separated sufficiently 

 to receive a row of sleeping persons between each of them. As 

 each new layer which is added to the structure is exactly pa- 

 rallel with the one below it 3 presenting the same elevations and 

 hollows, it was formerly a query in my mind how the worms 

 were able to place the first threads of these layers, for a scaffold- 

 ing on which to walk to complete the tissue. But, like many 

 other phenomena in nature which are a mystery to us at first, 

 this becomes quite simple when fully observed. The caterpillars 

 as already stated, repose in serene weather on the outer surface 

 of the nest, lying side by side as compactly as they can stow 

 themselves. Straggling individuals coming in from feeding at 

 this time, to spin their threads upon the surface of , the nest, and 

 finding it covered to a greater or less extent by their slumbering 

 comrades, proceed with their work as usual, traveling over the 

 backs of the reposing caterpillars to and fro in every direction, 

 thus spreading a blanket upon them as it were. These caterpil- 

 lars on awakening from repose, in order to make their exit, 

 crowd the thin threads aside in two or three places, thus form- 

 ing round holes through the web, which thenceforth become the 

 doors through which they pass in and out of the new apartment. 

 The old portions of the nest become foul, being filled with the 

 shrivelled cast skins and black grains excreted by the worms. 



