their Relation to Disease. 
11 
by several characteristics : (1) the position of rest: the whole body 
extends in a straight line at an angle with the surface on which 
the mosquito is resting ; in other mosquitoes the body-line is bent, 
owing to the more rounded or “humped” shape of the thorax; 
(2) in the great majority of the Anopheles the wings are spotted, 
whereas in the great majority of the others they are not; (3) in 
the female Anopheles the palpi are as long as the proboscis, while 
in most of the other genera they are much shorter; (4) when 
viewed under a microscope most mosquitoes are seen to have the 
Fig. 4.—Sitting Postures Adopted by Mosquitoes. 
(A) Anopheles; (B) Culex. 
abdomen covered with scales like those on a butterfly’s wing, but 
in nearly all Anopheles these scales are absent; (5) the larvae of 
Anopheles when at rest lie parallel with and touching the surface 
of the water, being held to the surface-film by a number of 
remarkable rosette-shaped tufts; the breathing organ is small. 
Other mosquitoes have larvae which hang head downwards in the 
water when at rest, and have no rosettes, but on the other hand 
have the breathing organ developed into a tube. 
There are about one hundred species of Anopheles known from 
different parts of the world. We have three in Britain, one of 
these being the species which spreads malaria in South Europe; 
