218 Annals Entomological Society of America [Vol. XII, 



disturbances/ When active feeding begins, the silk formation 

 becomes a more noticeable and important feature. Feeding 

 areas are surface excavations, usually with a depth greater than 

 the diameter of the caterpillar, across which is spun a fine, 

 somewhat substantial silk web, and under which the larva works 

 and rests. Frequently, the threads are tied across from one 

 radiating leaf vein to the adjacent one. with sufficient tension 

 to pull them slightly towards each other, thus producing a 

 depression beneath the web and providing a retreat for the 

 larva. These nets are of varying extent, but since they are a 

 constant accompanying feature of surface feeding, an attempt 

 was made to determine their significance. That they play 

 some real part in the life of the larvae is manifested by the fact 

 that while individuals occasionally leave the web-covered 

 tunnels for a certain amount of wandering, they almost 

 invariably return to the original ones or preempt others which 

 happen to be empty. Since the leaves of N el umbo rest upon the 

 surface of the water, wave-action, even of a slight degree, often 

 inundates them and, unless protected in some way, the young 

 caterpillars would be constantly exposed to the serious menace 

 of being washed off. A series of experiments showed that the 

 silk webbing constitutes an efficient safeguard against dis- 

 lodgment by waves. When the larvae are ensconced under 

 these webs, a vigorous dragging and threshing of the leaf 

 through the water in a manner more severe than the effect 

 of a heavy storm, in the protected coves, fails in most cases, to 

 wash them away. Possibly, these webs may serve, also, as 

 a partial protection against certain enemies and excessive light, 

 but according to the evidence at hand, its chief role is that of 

 an important adaptation to an ever present feature of the 

 aquatic environment. 



Peripheral feeding and accompanying silk formation differ 

 in character from the above-described activities. For varying 

 distances the thin edge of the leaf is folded over and tied by 

 strands of silk which extend from the upturned edge to the upper 

 leaf surface. Varying amounts of silk are used in this activity. 

 Instances were observed where the web was thick and brownish, 

 resembling, to some extent, a sort of cocoon. Often, however, 

 it is a fine, thin, dainty webbing through which the larvae are 

 plainly visible. Feeding invariably occurs under these webs. 

 Peripheral feeding is a very common habit nearly every infested 



