WERNER MARCHAND 155 



Tahanus higuUatus the shed larval skin adhering to the "puparium."^^ 

 Mitzmain had, however, not seen Paoli's work on the organ of 

 Graber, in which also mention is made of moltings. 



By Mitzmain the process of shedding the skin was observed in 

 Tahanus striatus in a great many instances. The time of molting 

 of a brood of larv£e is extremely variable, which is consistent with the 

 great variations noted in the time of development in general. The 

 process has been accurately noted in two individual larvae, although 

 observed superficially in numerous others. The three molts are simi- 

 lar in their general aspects, the main distinction being the more 

 profound changes produced in the insect at the later molts. 



The usual preparations for molting were observed in this species. 

 The premonitory signs were the refusal of food, uneasiness when 

 exposed to light, desire to find a remote corner, and finally the stiff- 

 ening of the cuticle. In one instance the larva was found in one 

 spot pressed against the glass for three days. Here, between the 

 sand and the glass of the jar, an excrementous cement was used to 

 fasten the end of the abdomen. This material holds the end of the 

 body very securely, although the remainder of the body requires free 

 lateral movement. By the time the ecdysis is completed, the head 

 has moved 3 mm. from the spot where preparations for the process 

 were made, while the anal end has retained its original position. 



The shedding of the skin usually requires several hours; in one in- 

 stance, due no doubt to interference by the observer, the time was 

 nearly twenty-four hours. In the first and second molts, splitting 

 of the cuticle begins at the thorax, resulting in the tearing out of the 

 entire head capsule which adheres to the molt during the remainder 

 of the process. The anal segments are molted finally and the larva, 

 emerging in its new skin, crawls its length on the cast skin and rests 

 alongside it for two or more hours. 



The first molt begins with larvae 7 days old, the majority molting 

 before the tenth day. The second molt usually occurs after an in- 

 terval of at least four days, and in some larvae as late as eight days, 



^^The use of the term "puparium" for the tabanid pupa should not be en- 

 couraged. The tabanid pupa is a true pupa, in contrast with that of muscids, 

 or syrphids, where the true pupa is enclosed in the last larval skin, justifying 

 the name puparium to dififerentiate it from a free pupa. 



