576 THE ANIMAL PARASITES OF MAN 



is covered with narrow curved golden-brown scales, the abdomen has basal pale 

 bands to the segments and the legs and proboscis are unhanded. 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 filarias 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 tibiae 

 are swollen. 



The black mosquito, Melanoconion atratus, Theoh. 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 larvae 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. 



Genus. Grabhamia, Theobald. 



" Mono. Culicid.," 1903, iii, p. 243.; 1907, iv, p. 284 ; and 1910, v, p. 277. 

 Allied to Culex, but separated by the wings having short fork-cells, mottled scales, 

 the median ones thick and also some of the lateral ones short and broad ; the last 

 two joints of the male palps are very slightly swollen. The eggs are laid singly, not 

 in rafts, and the larvae have short, thick siphons. Ten species occur and are found 

 in Europe, North America, West Indies and Natal. G. dorsalis, Meigen, bites 

 severely in Europe. G. sollicitans, Walker, is a great scourge along the New Jersey 

 Coast and at Virginia summer resorts and in Florida. It breeds in brackish wate r 

 and is the most common mosquito of the Atlantic seaboard. 



Genus. Pseudotaeniorhynchus, Theobald ; 

 Taeniorhynchus, Theobald, non-Arribalzaga. 



Differs from the former in having the whole wing veins clothed with dense, 

 broadish elongated scales. They occur in South America (T. fasciolatus, Arri.), in 

 Africa (T. tenax, Theob.), in Europe (T. richardii, Ficalbi). The latter bites very 

 severely. 



