216 OHIO EXPERIMENT STATION: BULLETIN 332 



its name, since it illustrates the bags, or baskets, of the full-grown 

 caterpillars. Many larvae spin somewhat similar objects but as a 

 rule these are not constructed until the time for pupation is near 

 at hand, while with the bag, or basket, worm one of the first larval 

 acts is to spin a covering for its body, and this bag is drawn about by 

 the larva during its feeding period. The fully-completed bag 

 sometimes measures as much as 2i/^ inches in length, though the 

 average length is about 1% inches. When opened, the larva within 

 will be found with its head near the larger end. It is dark in color 

 and gradually tapers from the head backward. 



The larval bag serves as a cocoon and pupation occurs within 

 its walls. The pupae of the sexes differ greatly in size, that of the 

 female bein^- much the larger. The adult male is a small, black 

 moth with beautiful feathery antennae. The moth flies at will, while 

 the adult female is a wingless grub-like creature which never leaves 

 the protecting bag but to drop out and die after her life duties are 

 completed. The eggs are deposited in a mass within the bag and 

 are mingled with a quantity of light-brown woolly material. Re- 

 ports made by various writers range from a few hundred to as 

 many as 3,000 eggs within a single bag. 



Life history and habits. — The winter is passed in the egg stage 

 within the shelter of the weatherproof silken-walled bag, and fur- 

 ther protected by the larval and pupal cases of the female. In May 

 or June the eggs hatch, the young larvae escaping through an open- 

 ing in the tip of the bag. As stated previously, one of the first 

 larval acts is the spinning of the bag, the details of the process 

 being lucidly set forth by Doctor Felt, (Memoir 8, New York State 

 Museum, p. 125). 



After the bag is constructed, the larva drags it about 

 wherever it goes by protruding the forepart of the body, thus per- 

 mitting the free use of the fore legs. If disturbed it quickly 

 retreats within its shelter. If, however, one attempts to draw the 

 caterpillar out of its bag, its body will be crushed or otherwise 

 injured before it will release its hold. 



The larva becomes full grown in August or early September. 

 It then seeks a favorable situation and secures its bag from the 

 upper end by a band of silk. Quite frequently the smaller branches 

 of the host are utilised for this purpose, and where the attack has 

 been severe large numbers of the bags may be observed so sus- 

 pended. (See Plate XXI, Figs. 1 and 2.) 



Soon after securing its bag, the insect passes into the pupal 

 period which lasts but a few weeks. The males then emerge and 



