250 BACOT : MOSQUITOES AND THE DANGER. OF MALARIA.
abdominal segments of the Anopheles larvae. These penetrate
the surface film of the water and supply sufficient floating
power to buoy up the larva when at rest. A further
characteristic of the Anopheles larvae is the quick reversibility
of. the head, rendered possible by the flexibility of its neck.
When the larva rises to the surface of the water, the dorsum of
its head is uppermost ; but. in order to feed, it may need to
reverse it, and this is done with lightning-like rapidity.
In the pupal state, Anopheles mosquitoes are less readily
separated from those of other groups than in their egg or larval
FIG 7.—CHARACTERISTIC RESTING-POSITIONS OF MOSQUITOES.—
A, Anopheles : B, Culex.
(By kind permission of the British Museum.)
condition, but the adult mosquitoes are very easy to distinguish.
As a rule, the wings of the Anopheles mosquitoes are spotted,
while the abdomen is hairy and devoid of scales. The female
palps are nearly, if not quite, as long as the proboscis, while in
most of the Culicinae genera they are very much shorter. As
the palps of the female Anopheles are carried in close proximity
to the proboscis, the naked-eve effect is that of a very much
thicker proboscis, the Culicinae proboscis appearing slender
in comparison. Finally, the resting-positions (fig. 7) of the two
groups differ markedly. Occasionally some species of Culex
adopt the Anopheles attitude more or less closely, but their
proboscis is always held at an angle which differs from the