LIFE HISTORY AND DEVELOPMENT. 107 



The hvpopharynx, which acts as the poison fang, is con- 

 nected Math a poison duct which has two branches run- 

 ning backward into the prothorax. The secreting glands 

 are in two paired systems, one on each side of the protho- 

 rax. Each system consists of three trifoliate glands, the 

 mid-gland being poisonous and the lateral salivary ; the 

 three ductules uniting into the branch of the poison duct 

 of its own side. 



LIFE HISTORY AND DEVELOPMENT. 



The breeding grounds of the mosquito embrace the 

 swampy hollows of low grounds, shallow rain pools, cis- 

 terns, ponds, and the wide expanse of salt or brackish 

 marshes extending up along the estuarine banks of slug- 

 gish rivers and the tide-invaded shores of sandy penin- 

 sulas, and also the wet area in thick woods. \ 



The first stages of the mosquito are found in the 

 s giall floating or suspended raft composed of an assem- 

 blage of many hundred eggs, each subconical in shape, 

 tapenng to a somewliaf rounded^or obtuse point notched 

 at the apex. The number of eggs in these rafts reaches 

 as high as three hundred, and become cemented together 

 by Tlie glutinous substance secreted at the oviposition. 

 The period of hatching extends about five or six days, 

 when the young larva makes its appearance after cutting 

 through the under surface of the egg. (Plate YIIL, 

 Fig. 2.) 



The young larva remains in the w^ater for about twenty 

 days, passing througli a series of three or four moults. 



The larva when full grown is about five millimetres 

 long, and is of a semitranslucent, grayish blackish color. 

 The head is small, subglobose. The first, second, and 



