102 
diptera. 
of the wings. When flying in the early Spring, gnats 
emit no sound. “The warmer the weather, the greater 
is their thirst for blood, the more forcible their flight, 
the motion of the wings more rapid, and the sound 
produced by that motion more intense . 55 The two 
mobt common house-inhabiting gnats are Culex pApieus 
( cilians ) and C. cninulcitus. The genus Corethra is 
remarkable for the curi¬ 
ous form and structure of 
the larva. It is a lon£ 
o 
worm-like creature as clear 
as crystal; the head is 
furnished with two de- 
flexed hooks; at the end 
„ of the abdomen is a 
Pcpa or Gnat {Coreiura plumiconiis ). n 
fan of hairs; unlike the 
larva of Culex, the Corethra larva suspends itself in 
a horizontal position in the water. There are two 
Larva of Gnat (Corethra plumicornis). 
curious oblong vesicles of considerable size in the 
thorax, and a pair of smaller ones towards the end of 
the tail; these organs are respiratory. The name of 
Mosquito is sometimes applied to a Simulium , some¬ 
times to a Culex. These insects are much more for¬ 
midable pests in some countries than the species are 
which are found in this country. Although the indi- 
