INSECTS AFFECTING PARK AND WOODLAND TREES 1 25 



cases of the female. A large number may be deposited by one female, as 



1284 were taken from one bag collected at Jericho L. I. and 523 occurred 



in one received from Everett Pa. ; while Mr A. Ciirault states that he has 



obtained as many as 2000 and 3000 eggs from individual females. The 



young appear sometime in May or early in June and begin by eating the 



softer portions of the leaf. They repair to the stems when not feeding and 



here it is that they sometimes cover their interesting shelters by biting off 



pieces of the bark and attaching them to the case. This habit was brought 



to my notice by Mr Joutel who, in the course of his studies of the insect, 



found many tiny brown cases on the older bark, green ones on the younger 



bark and occasionally party-colored ones. The gnawed condition of the 



bark showed where the color had been obtained. This is not the first 



record of this interesting habit for the same thing was observed by Mr S. S. 



Rathvon in 1867. He also mentions an instance of the young larvae of 



this insect hatching in his office and in the absence of food escaping to the 



floor where they proceeded to attach to their cases pieces of paper, leather, 



straw matting and even scales of lime, in fact taking anything at hand. 



The cases may also be constructed on the leaves. Dr Riley's exceedingly 



graphic account of this operation is as follows : 



The way in which this bag is prepared is curious [fig. 17]. The young 

 larva crawls on a leaf and, gnawing little bits from the surface, fastens these 

 together with fine silk spun from its mouth. Continually adding to the 

 mass, the larva finally produces a narrow, elongated band, which is then 



Fig. 17 Young caterpillar making its case on a leaf: deposition as it begins operations; ^=beginning the case; 

 f—caterpillar under strip and upside down; ./—caterpillar after turning; «=case more enlarged; /'—case com- 

 plete. (After Riley. U. S. Dep't Agric. Div. Ent. Bui. lo) 



fastened at both ends onto the surface of the leaf by silky threads. Having 

 secured itself from falling down by some threads, it now straddles this band 

 and, bending its head downward [fig. 17 d}, makes a dive under it, turns a 



