A verandah-trap hut for studying the house-frequenting habits of mosquitos and for assessing insecticides. I.—A description of the verandah-trap hut and of studies on the egress of Anopheles gambiae Giles and Mansonia uniformis (Theo.) from an untreated Hut

A description is given of a verandah-trap hut designed to assess the egress and survival of mosquitos escaping through the eaves of the type of window-trap hut used in insecticide testing in East Africa. Fifty-one per cent. of females of Anopheles gambiae Giles in all gonotrophic stages and 19 per cent. of those recently fed left the hut each night, with 15 and 30 per cent., respectively, of the egress occurring through the eaves. Ninety per cent of females of Mansonia uniformis (Theo.) in all gonotrophic stages and 91 per cent. of those recently fed left the hut each night, with 69 and 66 per cent., respectively, of the egress occurring through the eaves. It was concluded that, owing to the high proportion of individuals of M. uniformis that leaves by the eaves, the verandah-trap hut was of a more suitable design for studying the house-frequenting habits of this species, and of other species with similar habits, than the simple window-trap hut.