Appendix A. 71 



(Reduced from original) 



THE LIFE HISTORY OF MOSQUITOES. 



The mosquitoes (Cidicidae) are a family of two-winged insects with long 

 *T)eaks" and the instinct (in the female) for sucking blood. There are many 

 dilierent genera or kinds of mosquitoes, but the only ones which are of prac- 

 tical importance around New York are the two kinds called respectively 

 Culex and Anopheles. These can be easily distinguished from each other. 



Mosquitoes have four stages of development; the egg, the larva, the pupa, 

 and the winged insect. 



The eggs are very small, oval, black objects not so large as a fly-speck. In 

 the case, of Culex they are mostly stuck together side by side in little flat 

 masses, each mass containing several hundi;ed eggs. In Anopheles they are 

 only lightly adherent, end to end. The eggs are laid on water, upon which 

 they float. The end of the egg, after 36 or 48 hours (or more, in cool 

 weather) opens, and the larva escapes. 



The larva of Culex is the familiar "wriggler^' of pools and water barrels. 

 A larva of Culex is drawn in Fig. 1. It will be noticed that the insect in 

 this stage hangs downward, only its breathing tube or wind-pipe connect- 

 ing with the surface of the water. When disturbed, it dives and can re- 

 main without air for half an hour or more, though it usually rises to the 

 surface again in about half a minute. After the lapse of from one to thrc-e 

 weeks (according to the temperature of the water) when it has grown to 

 be about one-quarter of an inch long, the larva splits its skin and the pupa 

 (wliich corresponds to the chrysalis stage cf the butterfly) appears. 



The pupa is drawn in Fig. 2. It has two wind-pipes instead of one, and 



Fig. .2— Pupa of Culex. 



these are located near the head instead of at the tail-end. It flaps its tail 

 violently and sinks to the bottom of the water when disturbed. 



After from one to four days in warm weather the pupa in turn bursts its 

 skin up the back, and the adult insect appears, with wings, ready soon to fly, 



