806 AN INTRODUCTION TO ENTOMOLOGY 



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 re- 

 spiratory system. There are now two breath- 

 ing tubes, and these are borne on the thorax. 

 One of these is represented greatly enlarged 

 by Figure 1022, 6. At the tail-end of the 

 body there is a pair of leaf-like appendages, 

 witli which the insect swims, for the pupaj of 

 mosquitoes, and also of certain midges, differ 

 from the pupa3 of most other insects in being 

 active; but the pupte take no food. The 

 duration of the pupal stage is brief, usually 



^^o la?va~^^°^^u *r^' ^°^ ^^^^ ^^^^ ^^^° ^^ ^^^^^ ^^'^' ^^^^ *^^ 

 , arva, , pupa. ^^^^ splits down the back, and the winged 



mosquito carefully works itself out and 

 cautiously balances itself on the cast skin, using it as a raft, until its 

 wings are hardened so that it can fly away. 



All adult mosquitoes are commonly regarded as blood-sucking 

 insects and are feared on that account; but there are many species 

 that never suck blood at all, and of the blood-sucking species many 

 attack by choice birds and mammals other than man. It is only the 

 females that suck blood ; the mouth-parts of males are not fitted for 

 piercing the skin of animals. The males feed on nectar, the juices of 

 ripe fruits, and other sweet substances; this is also true to a certain 

 extent of females. 



The different species of mosquitoes differ greatly in their manner 

 of oviposition. Those most often observed about water-barrels, 

 Culex, lay their long, slender eggs side by side in a boat-shaped mass, 

 on the surface of the water (Fig. 102 1) ; 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 de- 

 veloped have dried out. In this case the eggs remain unhatched until 

 later rains or melting snow refill the pools. The eggs of some mosqui- 

 toes hatch very soon after they are laid; but with the majority of 

 species the winter is passed in the egg state ; and in the case of certain 

 species it is believed that the eggs may remain on dry ground several 

 years awaiting rain and then hatch. 



The family CiilicidcB is divided into two subfamilies, the Coreth- 

 rinas and the CuHcinas. 



Subfamily CORETHRIN^ 



This is a small group of mosquitoes including but few species. It 

 is distinguished from the Culicinae by the comparative shortness of 

 the proboscis, which is not much longer than the head and is not 

 fitted for sucking blood. 



The larvae of members of this subfamily are transparent; they 

 are predacious and capture their prey with their antennas; they 

 feed on infusoria, small Crustacea, and small larvae, including those 



