II 



FLIES WITH AQUATIC LARV.E 



177 



The food of the larva is altogether microscopic. 

 I have found the stomach filled with the flinty valves 

 of Diatoms and Desmids, with here and there bits of 

 a small Crustacean. A pair of fringed appendages, 

 one on each side of the head, are employed, like 

 the similar apparatus of the Gnat larva, in sweeping 

 particles into the gullet. 



Th-e body of the larva is cylindrical, and dilated in 

 the hinder part of the abdomen. The mouth-parts 

 are represented in Fig. 61. In addition to these are 

 seen the fan-like appendages, each provided with 



Fig. 60. — Head of larva of Simulium, dorsal view, showing eye-spots, antennae, and 



fringed appendages. 



about fifty long filaments, which are feathered along 

 one side, and sweep the food into the gullet. Since 

 the subsistence of the larva depends upon these 

 delicate organs it is not surprising to find that great 

 pains are taken to keep them from being clogged. 



N 



