The malaria problem at an operational aerodrome beside a lake in Egypt is stated, and the bionomics of the mosquito vector described. The chief control measure was the spraying of Paris Green from aircraft over the breeding places of the vector. In 1944, spraying was extended along the lake edge to the large native village nearby, where the bulk of the breeding occurred. A number of experiments to test the effectiveness of the spraying are recorded, and details given of the spraying experience and difficulties encountered in 1944. Two modifications to the aircraft, one being the introduction of a hand operated agitator in the dust hopper, the other simplifying the control of the dust outflow were introduced. The incidence of primary malaria at the aerodrome, reduced following spraying in 1943, fell still further in 1944, and in that year at the village, the incidence fell to about one third of that of the three proceeding years. The requirements for successful aircraft spraying are discussed in the light of past and present experience
