352 



INTRODUCTION TO ZOOLOGY 



CHAP. 



The Horn-bearing Fly (Ceratopogon tricolor). 



Ceratopoqon, like Tani/pus. 

 The Larva. .,, , -f , y n , Jr 



will probably first come under our 



notice in the larval form, for the larva is 

 very common on the surface of stagnant 

 ponds where there is a plentiful supply of 

 small filamentous Algae. The larva has a 

 very slender, rather transparent, thread-like 

 body, which, when touched, immediately be- 

 comes rigid; it may be half an inch long. 

 The head is small, and bears four tiny, very 

 black eyes, and a pair of strongly incurved 

 black mandibles. There are twelve segments 

 to the body, and the last one bears a circle 

 of black bristles which can be moved forwards 

 or backwards. Right 

 at the tip are also Imago, 



five little transparent 

 processes which can 

 be protruded or 

 withdrawn; these are 

 probably gills. The 

 whole surface of 

 the body is striated 

 with fine longitudinal 

 lines. A pair of air- 

 tubes can be seen 

 through the trans- 

 parent skin. The 

 larva swims like an 

 eel through the water, 

 with a very rapid 

 motion. 



In due 

 The Pupa. .. 



time the 



last larval skin is 



thrown off, and the 

 pupa appears at the surface, where it hangs vertically or slightly 

 curved, never curled up like the gnat or Tanypus pupae. It has 

 two respiratory tubes at the upper end, and on the last segment a 



FIG. 276. 



Ceratopogon bicolor 



(larva). 

 (Much enlarged.) 



a, Gills ?;&, stiff hairs. 



FIG. 277. Imago and Pupa 

 of Ceratopogon. 



