1922] Frost: Ecdysis in Tmetocera ocellana 165 



THE MOULTING PROCESS. 



The process of moulting, as in all insects, is a delicate one. 

 The larva at this time is weak and helpless and very susceptible 

 to injury. Nature, however, has provided ample means of 

 protection during this period. The larva never moults in the 

 open, but always conceals itself in some manner. Sometimes 

 it may be a curled leaf with a few silken threads, but more 

 often it forms a well constructed silken moulting case. This 

 case may be entirely closed or partly open at one or both ends. 

 The larva often moults within its feeding case, which serves as 

 a means of protection during the entire life of the larva, but 

 at this time provides special protection. As a rule, moulting 

 occurs in a closed moulting case. 



The feeding case is composed of a mass of silken threads 

 tightly woven together into a trumpet shaped tube somewhat 

 resembling the feeding tube of the Apple leaf crumpler {Mineola 

 indigenella Zell.) but is smaller and neater. The frass is 

 utilized by the larva and woven into this silken tube, giving it a 

 blackish color and forming a hard protective covering. 

 Immediately following a moult, within the feeding case, the 

 moulted skin and head capsule will be found inside the feeding 

 tube. These are pushed by the larva to the end of the case 

 where they become entangled with the silken threads of the 

 case and are later imbeded in the silk and the frass of the 

 case. 



It is possible to determine when a moult is approaching. 

 Several hours or even a day before hand the approaching 

 moult is indicated by a whitish membraneous area between 

 the head and the prothoracic shield and a decided constriction 

 at this point. The moult follows shortly afterwards. 



When ready to moult the skin loosens at the thorax and the 

 old integument, including the prothoracic shield, moves off 

 the posterior end of the larva. The larva frees itself by -crawling 

 out of the skin. The head capsule comes off separately and 

 in several cases under observation popped off about the same 

 time the larva freed itself from its skin. Only a short time 

 elapses from the first indication of a moult until the skin is 

 shed. In one instance a larva was in the process of the fourth 

 moult at 4:52 P. M., the old head capsule had worked half 



