3 io 



THE MOSQUITOES 



of the body, the true end of which terminates in four flap-like paddles. If you di- 

 vide the length of the siphon by the breadth, you get what is known as the siphon 

 index. In Culex the siphon is long and slender, in Stegomyia it is short and barrel- 

 shaped. When at the surface the Culex larva has its siphon almost vertical and the 

 body at an angle of about 45. 



The Stegomyia larva hangs more vertically. As a rule, the hairs proceeding 

 from the sides of Culex larvae are straight and the head relatively large. There 

 are also no palmate hairs along the sides. 



The Anophelinae larvae have a small head which is capable of being twisted 

 around with lightning-like rapidity. They are darker in color and have no siphon; 



^''" 



Fig. 92. Metamorphosis of mosquitoes, i, 2, 3, 4, and 5, Eggs, larva, pupa, 

 and heads of male and female Culex; 6, 7, 8, 9, and 10, eggs, larva, pupa, and heads 

 of male and female Anopheles; n, 12, 13, 14, and 15, eggs, larva, pupa, and heads 

 of male and female Stegomyia. 



float parallel to the surface of the water; have long lateral branching hairs, and on 

 the sides of each of the five or six middle abdominal segments they have a pair of 

 palmate hairs. These palmate hairs are supposed to aid them in keeping their 

 position on the surface of the water. The larvae are usually called "wigglers." 

 The duration of the larval stage is from i to 2 weeks, according to the temperature. 



THE PUP.E. 



These have a bloated-looking cephalo-thorax and a shrimp-like tail the latter 

 the abdomen. Very important in examining them with a lens is to note the char- 

 acteristics of the siphon tubes which project from the dorsal surface. These siphons 



