190 APPLE-TREE CATERPILLAR EXERCISE AND REST. 



uals who are every moment returning there from feeding. 

 Having taken this journey to the end of the limb and back and 

 thus had the amount of exercise which they require, they crawl 

 into the tent and there compose themselves to rest. Thus when 

 but a few straggling worms remain upon the limb on which 

 they have all been feeding, a few others will be seen journeying 

 homeward to the tent, a multitude of others will be seen walk- 

 ing about upon the surface of the tent spinning their threads, 

 many more will be seen traveling upon both of the branches 

 which fork off from the tent, some of them going out and others 

 coming in, whilst the inside of the tent is black with the multi- 

 tude that has completed their labors and retired to repose. The 

 ranks of each of the sections first specified gradually become 

 thinner, until at last all have withdrawn into the tent. 



Dr. Harris (Injurious insects, 2d ed. p. 287) says these cater- 

 pillars "all retire at once when their regular meals are finished;" 

 and it must hence be inferred from his account that it is after 

 reposing and before going out to feed that they strengthen their 

 nests with additional threads. But from repeated observations 

 I am assured that it is after feeding and before retiring to rest 

 that they add the new threads to their nests. The routine in 

 which they pass their lives consists of the three acts, feeding, 

 exercising, and resting. Dr. H. also says that "At all times 

 when not engaged in eating, they remain concealed under the 

 shelter of their tents." But upon warm days when the sky is 

 serene, they do not retire into their tent at all, but repose upon 

 its outside, which is literally covered with them, and so black 

 that at first sight persons suppose the nest to be a black hat 

 placed in the tree. They are very sensitive to atmospheric 

 changes. Upon rainy days they remain within their tents and do 

 not go out to feed; yet I have repeatedly seen them feeding at 

 night when the leaves were wet with dew, and still oftener in 

 the morning before this moisture had evaporated. On the eighth 

 of May, the worms on a bush which I had taken into my study, 

 went out of their nest to feed in the morning; but it coming on 

 to rain out of doors, they all quickly returned into the nest. 

 I hereupon kindled a fire in the stove and the warmth had no 

 sooner commenced diffusing itself through the room than these 



