27 
Structure of Larvae. 
species. It possesses three pairs of lateral tufts of hairs, which 
are supposed to represent the three metameres, the pro-, meso-, 
and metathorax. Each tuft springs from a little lump or 
tubercle, and the component bristles are themselves clothed 
with filaments. There are also other small tufts, two project 
ing forwards in front, and others arising from the terga. The 
abdomen is much narrower and longer than the thorax, and 
consists of nine segments, each being provided with a lateral 
tuft of bristles and other smaller hairs, both on the dorsal and 
ventral surfaces. These hairs may be single or in groups. From 
the eighth segment there arises on the dorsal surface a tube, the 
respiratory siphon, of varied length and breadth. In the filaria- 
carrying mosquito ( C . fcttigans) it is very long and narrow, as 
long as half the abdomen in some stages of the larva. In 
C. annulatus and 0 . pipiens it is as thick as the last abdominal 
segment. In this respiratory tube run the two tracheae. The 
end of the tube is provided with valved and guarded openings. 
The last segment bears on its venter the anus, which is sur¬ 
rounded by four foliate and delicate expansions, each being 
richly provided with air-tubes. A little in front of these fin- 
like processes are two tufts (lateral) of compound hairs, and there 
are also a number of hairs arising above the fin-like processes. 
Four large pigment spots may be seen in the living larva, 
probably glands, with hepatic functions, lying internally. It is 
the tip of the respiratory siphon only that touches the surface 
film of the water, and the four anal plates (wrongly stated five 
by Miall *) do not touch the surface at all. Professor Howard, 
whose life-history of Cnlex pungens j* is the best yet written, states 
that he believes “ these gill flaps may be functional in the young 
larva, but that they largely lose their office in later life.” 
The chief characters, then, of Culex larvae are: (1) the large 
head, (2) still larger thorax, (3) the nine segmented abdomen, 
with the rather long siphon arising from the eighth segment, 
and the presence of four fin-like flaps at the end of the apical 
metamere. In colour Culex larvae are pale or deep dirty brown 
or straw coloured, some pale grey, others with a greenish tinge. 
Stegomyia larvae (Fig. 16).—In a paper J sent me by 
Captain James is a figure of a larva that he calls the larva of 
* “ Aquatic Larvae,” p. 98. 
t Bull. No. 4. New Series, U.S. Dept. A<rri. (1896), p. 12. 
X ‘‘Indian Medical Gazette,'” vol. xxxiv., December 1899. 
