DIPTERA 
55 
The time of these changes from 
egg to larva, from-larva to pupa, 
and from pupa to adult depends on 
the temperature. Warm weather 
shortens the time and cold weather 
lengthens it. 
In the United States there are 
three distinct kinds of mosquitoes. 
(1) The common mosquito is known 
by the technical name of Culex 
(ku'leks). It is not known that the 
Culex carries in its body any disease 
germs harmful to men, therefore it 
is regarded as harmless, although a 
source of great annoyance to those 
who frequent the woods or seashore 
during the summer. (2) Anopheles 
(a-nof'e-lez) is the scientific name 
of a second kind of mosquito, which 
is also generally distributed, but is 
not so numerous as the Culex. The Anopheles often carries 
in its body the germs that cause the disease called malaria. 
(3) Stegomyia (steg-o-mi'ya) is a mosquito common in the 
southern part of the United States. It is the insect which 
carries the germs of 
yellow fever from one 
person to another. 
It is fortunate that 
the mosquitoes have so 
many enemies. The 
“ wigglers ” are preyed 
upon by the larvae of 
the dragon flies, by 
small fish, and by water 
Figure 47. — Eggs and Larwe of Culex. beetles ; while the adults 
Figure 46. — Culex and 
Anopheles. 
