DISTRIBUTION OF DISEASE GERMS 



109 



125. The life history of the mosquito. Mosquito eggs are 

 laid in little groups on the surface of the water (fig. 55, A). 

 When the eggs hatch, the individual emerging from each egg is 

 a little squirming 

 insect-like crea- 

 ture, technically 

 called a larva but 

 popularly known 

 as a "wriggler" 

 (fig. 55, (7). The 

 eggs may hatch 

 in less than a day 

 after they are laid. 

 The larvae live 

 about seven days 

 in warm weather, 

 but longer if the 

 temperature is 

 cool or if food is 

 scarce. Finally, 

 each larva changes 

 into another form, 

 the pupa (fig. 55, 

 F}, which lives in 

 the water three 

 days or more. The 

 pupa changes into 

 an adult mosquito. 

 The adult lives in 

 the air, but lays 

 eggs on the sur- 

 face of the water. 

 When the eggs are produced, another life cycle is begun. 



In its larval stage the mosquito feeds upon very small liv- 

 ing things in the water. It frequently comes up and protrudes 



FIG. 55. The common mosquito (Culex) 



A, egg raft ; B, eggs ; C, young " wrigglers," or larvae ; 



D and E, views of larvae ; F, pupa ; G and H, females ; 



7, male. A, B, C, G, H, and /, somewhat enlarged ; Z>, 



E, and F very much enlarged. After Howard 



