This large genus still contains many forms which should be excluded. The species normally have narrow curved median head-scales, and similar ones on the scutellum; the female palpi are shorter than in the former genus and the male palpi are pointed; the lateral vein-scales are narrow and linear.
The type is Culex pipiens, Linn., the common gnat of Europe. The thorax is covered with narrow curved golden-brown scales, the abdomen has basal pale bands to the segments and the legs and proboscis are unbanded. The stem of the first submarginal cell is always less than one-fifth the length of the cell. It lays its eggs in rafts in water-butts, etc., and even in the foulest water. They are first deposited in England in June and July, and again soon after hatching in August. In some districts this gnat bites man viciously, in others not at all.
The common tropical gnat (Culex fatigans, Wied). This resembles the European Culex pipiens, but can always be told by the stem of the first submarginal cell always being much longer than it is in C. pipiens. This is one of the species that has been proved to transmit filariæ to man, etc. Varieties of it occur in almost every country between 40° N. and S., having a very similar range to S. fasciata. In all countries it appears to be connected with the transmission of Filaria bancrofti, and it is also said to carry the micrococcus of dengue fever.
Genus. Melanoconion, Theobald.
“Mono. Culicid.,” 1903, iii, p. 238; 1907, iv, p. 507; 1910, v, p. 455.
This genus is composed of eight species, most of which are small black gnats which bite viciously and which occur in swamps and jungles. They can at once be told from Culex by the veins of the wings having dense broadened scales on their apical areas and along the upper costal border. The femora and apices of the tibiæ are swollen.
The black mosquito, Melanoconion atratus, Theob. This small gnat is a very troublesome pest in swamps in the West Indies. The female bites both by day and by night, and the bite causes severe irritation. The larvæ live in permanent ponds. It is almost black in colour, but sometimes presents a dull coppery sheen; each segment has small lateral basal white spots. Length 2·5 to 3 mm.
It occurs in Para and British Guiana as well as in the West Indies.
Ordinary mosquito netting is no use for keeping off this pest.