viii. B, 3 Mitzmain: Biology of Tabanus striatus Fabricus 207 



seems to be synchronous is the hatching of the eggs. After 

 that the variations in time of development are extreme. In 

 Tabanus striatus, for example, some larvae twelve days old meas- 

 ured 3 millimeters, while others under precisely the same con- 

 ditions measured fully 11 millimeters. In another instance 2 

 flies emerged as well-developed imagoes October 31, while 27 

 of the same brood still remained apparently healthy in the larval 

 stage December 20, 



THE ECDYSES 



In the very meager literature available I have been unable 

 to find any reference to the molting process in TabanidaB. It 

 is referred to indirectly by King (2) at Khartoum, who found 

 in T. biguttatus the shed larval skin adhering to the puparium. 



The process of shedding the skin was observed in a great 

 many instances. The time of molting of a brood of larvae is 

 extremely variable, which is consistent with the great varia- 

 tions 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 

 similar 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, un- 

 easiness when exposed to light, desire to find a remote corner, 

 and finally the stiffening 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 milli- 

 meters from the spot where preparations for the process are 

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



The shedding of the skin usually requires several hours; 

 in one instance, due no doubt to interference on the part 

 of 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 



