2g8 



THE STUDY OF INSECTS 



sucking. They consist of six bristles or stylets enclosed in a sheath 

 formed by the" labium. In those members of the subfamily, Corethrincs, 



the mouth-parts are short and not 

 adapted to sucking. 



The different species of mosqui- 

 toes differ greatly in their manner of 

 oviposition. Those most often ob- 

 served about water-barrels, Culex, 

 lay their long, slender eggs side by 

 side in a boat-shaped mass, on the 

 surface of the water (Fig. 513); 

 species of Anopheles deposit their 

 eggs separately upon the surface of 

 the water ; and many Aedes lay their 

 eggs on the ground after the pools in 

 which they were developed have 

 dried out. In this case the eggs re- 

 main unhatched until later rains or 

 melting snows refill the pools. The 

 eggs of some mosquitoes hatch very 

 soon after they are laid; but with 

 Fio. 513. — a glass of water containing eggs, iarvs, the majority of species the winter 



and pupa, of mosquitoes. fe passed in ' the egg state _ 



The larvae of mosquitoes are all aquatic. They are well known and 

 are commonly called " wigglers," a name suggested by their wriggling 

 motion as they swim through the water. They vary in details of struc- 

 ture but the larva of Culex will serve to illustrate the general form of the 

 body (Fig. 514, a). The head and 

 thorax are large and the abdomen 

 is slender. The next to the last ab- 

 dominal segment, the eighth, bears 

 a breathing-tube; and when the 

 larva is at rest it hangs head down- 

 ward in the water, with the opening 

 of this tube at the surface (Fig. 

 513). At the end of this tube 

 there is a rosette of plate-like 

 lobes (Fig. 515, a) which resting 

 on the surface film, keeps the larva in position. 



The food of most mosquito larvae consists of organic matter which 

 they find in the water in which they live. Some larvae are predacious 

 on small aquatic animals. 



The pupae of mosquitoes like the larvae are aquatic, but they differ 

 greatly in form from the larvae (Fig. 514. &)■ The head and thorax are 

 greatly enlarged and are not distinctly separated, while the abdomen is 

 slender and flexible. With the change to the pupa state a remarkable 

 change takes place in the respiratory system. There are now two breath- 

 ing tubes, and these are borne on the thorax. 



Only female mosquitoes suck blood and many of these attack birds 

 and mammals rather than man. Some species are said not to suck blood 

 at all. Male mosquitoes feed on nectar, the juices of ripe fruits and 

 other sweet substances. 



Fig. 514. — Mosquitoes. 

 a, larva; b, pupa. 



end 

 of 

 larva; b, breathing 

 tube of pupa. 



Fig. 5i5- 

 breathing-tube 



