10 U.S. NATIONAL MUSEUM BULLETIN 244 



plants {Ostrya, Robinia, Ulmus, Vinca minor, etc.) without any 

 noticeable cessation in feeding from the changing of hosts. 



The construction of a portable case by the larva is one of the most 

 obvious features of the family. This unusual habit, however, is not 

 restricted to the Psychidae, but it also occurs in the closely related 

 family Tineidae as well as in such groups as the Coleophoridae and 

 Lacosomidae. The basic construction of the case is of silk, which is 

 spun from the labial glands of the larva. Various types and arrange- 

 ments of ornaments usually are applied to this foundation. Both 

 extremities of the case are open and are usually very flexible for a 

 short distance from either end, thereby greatly facilitating the closing 

 of the two apertures by the larva inside. The overall appearance of 

 the case may var}^ considerabl}^ among different species of psychids, 

 and it frequently may be diagnostic for a given species. In several 

 instances, however, the architecture of the larval bag definitely is 

 known to be of no specific importance. The Macro-Psychina fre- 

 quently differ from the more primitive psychids in having the larval 

 cases often covered with rather large fragments of plant material; on 

 the other hand, the sacks of the Micro-Psychina are more tineid-like 

 in construction: the exterior is nearly bare or it is covered often with 

 minute fragments of lichens and/or soil particles. 



Newly emerged bagworms very soon begin to construct somewhat 

 conical cases that at first are carried upright. As the larva grows, 

 the bag is enlarged correspondingly and, because of the increased 

 weight, is carried in a pendant manner in which the insect clings to 

 some support by means of its well-developed thoracic legs. The anal 

 prolegs play an important role in retaining a firm grasp on the case. 

 The anterior four pairs of abdominal prolegs, having lost a major 

 part of their function, are reduced to mere vestiges. 



Pupa. — All members of this family undergo pupation within the 

 larval case. In preparing for pupation, the mature larva first firmly 

 secures the upper end of the case to some support, thereby sealing 

 the normal entrance. The larva of both sexes then reverses itself 

 with the result that the head is directed toward the lower end of the 

 case, and it pupates in this position. The male pupa of the Macro- 

 Psychina is approximately half the size of the female, and it pos- 

 sesses the normal sheaths for the various body appendages; that of 

 the female is very simple, with the leg and antennal sheaths being 

 present only in the more primitive group. The length of time in this 

 stage varies considerably within a species, between sexes, and among 

 the species. In those that do not hibernate in this stage, the interval 

 for the pupal instar may range from less than a week for some species 

 to as long as 111 days for the male of 0. kirhyi (Stephens, 1962). 



Adult. — Immediately before the emergence of the adult, the male 

 pupa gradually pushes itself partly out of the bag. Soon after leav- 



