152 THE EARLY STAGES OF TABANTD^ 



jars, and the remaining six larvae were so small as to be easily over- 

 looked. The count of the larvae from the individual jars showed a 

 loss of twelve, or less than 5 per cent. Allowing 5 per cent for loss 

 from other causes, it appeared that above 85 per cent of the larvae 

 kept together in the large jar was destroyed through cannibalism. 



It has been observed by Hine in other species that a Tabanus larva 

 is enabled to survive for a few days in the absence of food. In this 

 species, likewise, there seems to be a decided resistance to starvation, 

 two instances showing periods of ten and twelve days. 



Mitzmain found the movements of the body to be in general similar 

 to those of larvae of the muscid type. There is a general progressive 

 peristaltic movement, invariably accompanied by a decided telescop- 

 ing of the segments. The head is raised as the prolegs of the anal 

 end push the body forward, then it is lowered. The mouth is pro- 

 jected when the head capsule is extended, but recedes quickly when the 

 glass sides of the container or any obstacle is encountered. The larva 

 can easily move backwards for a considerable distance. This it does 

 if wedged in a tight place or in capturing food when it retreats into a 

 channel previously made in the sand. 



The larvae readily adapt themselves to a watery medium. They 

 can remain submerged for several minutes at a time without apparent 

 discomfort. When placed in deep water the movements of the 

 body consist of a general struggling without apparent definite pur- 

 pose. At any rate, there is little or no progression, the body doubles 

 like a bow, the head and tail meeting, then straightens with a whip- 

 ping action. In swimming, the body is held along the surface of the 

 water and the syphon is extended towards the air in a manner sug- 

 gestive of the larva of an anopheline mosquito. The principal move- 

 ment observed is that of simple telescoping of one segment into an- 

 other. When speed is required or an obstruction is to be passed, 

 there is a vigorous whipping movement of the syphon laterally, 

 towards and away from the head. This latter movement is also 

 noted when the insect is disturbed. 



When a young larva is placed in water containing entomostracans 

 or other minute animals, a barely perceptible churning of the liquid 

 occurs in the region of the mouth. This disturbance is no doubt 

 caused by the movements of minute tentacles which assist in procur- 



