2/8 OUR INSECT FRIENDS AND FOES 



of the body like that of Culex, the stigmatic 

 opening on this segment being in the form of 

 a large quadrilateral space with comb-like 

 processes upon each side. During the larval 

 stage of their existence both Anophelines and 

 Culex rise to the surface of the pool and stick 

 the processes on the eighth body-segment above 

 the surface film of water to take in air; that is 

 to say, they rise tail first, and, so to speak, 

 " breathe through openings in their tails." The 

 pupal stage, which is also spent in the water, is 

 quite as active as that of the larval period* 

 although now the insect ceases to feed, and 

 undergoes a great change in its outward appear- 

 ance, the whole of the head and chest being 

 swathed in a helmet-like sheath, beneath which 

 the wings, slender legs, and complex mouth- 

 parts of the adult mosquito are formed. The 

 insect no longer rises tail first to the surface of 

 the pool, but head first, for the apparatus for 

 taking in the air supply is no longer situated 

 upon the eighth body-segment, but now consists 

 of two tubular horns on the back of the thorax 

 which are thrust above the surface of the water 

 when the pupa rises to take in air. The pupa 

 does not move through the water with the 

 curious wriggling motion of the larva, but 

 swims in sharp jerks by means of its tail and its 

 two leaf-like terminal organs. At the close of 

 the pupal stage, the insect rises to the surface 

 of the water and flattens itself out, the thorax 

 spilts down the back, and the adult mosquito 

 gradually emerges, and rests upon the raft 

 formed by the empty pupa-case until its legs 



