51 
Pupae of Culicidae . 
with great rapidity. The pupa does not appear, however, to be 
able to remain under water except by great exertion; as soon as 
it ceases moving it floats up to the surface again. Culicid pupae, 
like the larvae, breathe the air through protruding spiracles, but 
these air-tubes, instead of being at the tail end as in the larvae, 
are placed on the dorsum of the thorax as two trumpet¬ 
shaped structures of somewhat different form in the different 
genera. 
Culex pupa (Fig. 15).—In Culex the head of the pupa is 
placed underneath the large rounded thorax, and differs materially 
from the head of the larva ; the mouth parts, labrum, labium, 
mandibles, maxillae and palpi, have become much elongated, as 
also have the antennae, which are seen in their sheaths lying 
above the thorax just beneath the wings ; the eyes are large, 
oval, and prominent. 
The thorax is largely developed, and shows the outline of the 
legs, which are partly hidden by the wings, except most of the 
first and part of the second, and above them the antennae, 
whilst the greater part is taken up by the large flat, short wing- 
cases, which extend downwards and backwards from the sides. 
Behind each of these is a small roughly triangular piece, the 
cover of the future halteres. On the surface of the dorsum 
of the thorax, arising just above or in front of the roots of 
the wing-cases, are the respiratory horns, which are struc¬ 
turally of generic importance. These trumpet-like structures 
are tubular and cylindrical, rather narrowed at their bases, free 
at one end, this end being open and quite unprotected, excejyt 
for a number of fine hairs which project from the inner side of 
the tube ; the opening is oblique, and there is a slight notch on 
the inner side. The cavity of these siphons communicates direct 
with the tracheal system. In the young pupa the legs, as seen 
through the leg cases, are unjointed, but by degrees all the joints 
are represented before the pupa reaches maturity. The abdomen 
is, like the larva, composed of nine segments, and is flattened 
dorso-ventrally. The eighth segment bears a pair of large fins 
(thin oval plates), each fin being supported by a hard mid-rib, 
which in some projects beyond the hinder border (Fig. 15). The 
ninth segment is small, and has the opening of the anus present 
on it, and also a pair of blunt processes, said to be larger in the 
male than in the female. On the abdominal segments are also 
numerous bristles, particularly on the last few segments. The 
