Mosquitoes and Malaria 
195 
Larva: When at rest floats in 
a horizontal position beneath the 
surface film. No respiratory 
tube but instead a flattened 
area on the eighth abdominal 
segment into which the two 
spiracles open (fig. 128). 
Adults: Palpi in both sexes 
nearly or quite as long as the 
proboscis. Proboscis projecting 
forward nearly on line with the 
axis of the body. When at rest 
on a vertical wall the body is 
usually held at an angle with the 
vertical (fig. 128). Wings fre¬ 
quently spotted (fig. 130). 
When at rest (with few excep¬ 
tions) floats suspended in an 
oblique or vertical position, or 
more rarely nearly horizontal, 
with the respiratory tube in 
contact with the surface film 
(fig. .128). 
Palpi short in the female, in 
the male usually elongate. Pro¬ 
boscis projects forward at an 
angle with the axis of the body. 
When at rest on a vertical wall 
the body is usually held parallel 
or the tip of the abdomen in¬ 
clined towards the wall (fig. 128). 
Wings usually not spotted. 
(a) Normal position of the lar¬ 
vae of Culex and Anopheles in 
the water. Culex. left; Ano¬ 
pheles, middle; Culex pupa, 
right hand figure. 
These malarial-bearing species are essentially domesticated 
mosquitoes. They develop in any accumulation of water which 
stands for a week or more. 
Ponds, puddles, rain barrels, 
horse troughs, cess-pools, cans, 
even the foot-prints of ani¬ 
mals in marshy ground may 
afford them breeding places. 
It is clear from what has been said regarding the life cycle of the 
malarial parasite that the mosquito is harmless if not itself diseased. 
Hence malarial-bearing species may abound in the 
neighborhood where there is no malaria, the disease 
being absent simply because the mosquitoes are unin¬ 
fected. Such a locality is potentially malarious and 
needs only the introduction of a malarial patient who is 
exposed to the mosquitoes. It is found that such patients 
may harbor the parasites in their blood long after they 
are apparently well and thus may serve as a menace, 
just as do the so-called typhoid carriers. In some 
malarious regions as high as 80-90 per cent of the natives 
are such malaria-carriers and must be reckoned with in 
antimalaria measures. 128 (6) Norma 
Based upon our present day knowledge of the life cycle c°u S i'e x° n a ni 
of the malarial parasite the fight against the disease fh n e °waiL S °" 
