344 INTRODUCTION TO ZOOLOGY chap. 



water, and may upset it and drown the fly. However, when 

 once the legs are free this danger is over, for they immediately 

 spread out on all sides of the old skin on the surface film of 

 the water, making the equilibrium of the body stable once 

 more, and so the insect can rest secure until strong enough 

 to fly away and fulfil her destiny. 



The Spotted Gnat or Mosquito {Anopheles maculipennis). 



The Spotted Gnat also occurs in Britain, and is widespread 

 in warmer countries. It can be recognised by the four dark 

 spots on each wing ; also, when at rest, it does not hold 

 its back legs so high in the air. This is the gnat which is 

 responsible for the malaria, or ague, of South European and 

 tropical countries. The disease is due to a microscopic germ 

 in the red blood-corpuscles of man, and the gnat, passing 

 from one victim to another, and drawing blood from each, 

 carries the infection and thus spreads the disease. In England 

 this disease seems to have been stamped out, and so the stab 

 of this Spotted Gnat is no more harmful here than that of 

 any other. 



The eggs of the Spotted Gnat can be recognised by the 

 fact that they are not laid in a raft-like mass, but are spindle- 

 shaped, and lie separately and horizontally on the water, 

 supported by two little lateral air-sacs like small blisters. 



The larme also lie horizontally on the surface, and have a 

 very short, forked air-tube ; they have, projecting from the 

 end of the tail, an unpaired row of stiff hairs and three tufts 

 of hairs. 



The pupae are very similar to those of Culex, but arc 

 green. 



The Phantom-fly (Corethra plumicornis). 



Corethra is another member of the Culicidae. It is better 

 known perhaps in its larval than in its winged state, for its 

 curious transparent " phantom larva," when once seen, cannot 

 but arouse interest. 



The winged insect closely resembles a gnat, 

 ' and the male has similar conspicuous plumed 

 antennae, whilst in the female they are small. 



The eggs are laid on the surface of a fairly clean pond in 

 a flat sheet of jelly, in which they lie in spiral lines. 



