POND LIFE 



673 



a fresh supply of air ; 

 for at this, the larval 

 stage of their exist- 

 ence, they breathe 

 through the curious 

 tail-like organ. They 

 feed chiefly upon the 

 microscopic forms of 

 life that swarm in 

 the pond, but they 

 are also great can- 

 nibals, and devour 

 their younger and 

 weaker brethren. 

 They grow fairly 

 rapidly, and from 

 time to time, in 

 consequence of their 

 increasing size, cast 

 their skins. Just 

 before the final larval moult they alter 

 in shape, ha\-ing a more bulky appear- 

 ance in the region of the head and 

 chest or thorax, until at last the skin 

 is cast and the change which has been 

 taking place beneath it is revealed. 

 Then the head and chest are seen to be 



THE GNAT 



NYMPH 

 THE 



enclosed in a casing 

 reseml:)hng in shape 

 a kind of fireman's 

 lielmet, the body 

 has shortened, and 

 the double tail has 

 changed to an ex- 

 tremity rather like 

 the tail of a lobster. 

 From the back of 

 the " helmet," near 

 the base of the head, 

 spring t w o short 

 tubes, and within 

 the semi-transparent 

 covering of the 

 " helmet " can be 

 seen the slender 

 folded legs and wings 

 of the future adult 

 Gnat. The insect has now reached the 

 active nymph stage of its life, and now 

 rises to the surface head first, poking 

 two tubes on its back, through 

 takes in the air supply, 

 the final transformation of the 

 about to take place the active 



RISES HEAD 

 SURFACE. 



FIRST TO 



out the 



which it 



When 



Gnat is 



HEAD OF MALE GNAT WITH 

 ANTENNA. 



PLUME-LIKE 



HEAD OF FEMALE GNAT 

 LANCET, ETC. 



WITH 



