Toxicity of Limewash containing DDT or “Gammexane” to Mosquitos (Aëdes aegypti, L.)

Abstract

Limewashes containing DDT or “Gammexane” were tested for insecticidal action on mosquitos (Aëdes aegypti) by confining the latter in cages with treated walls and ceilings. Only about 60 per cent, of the total internal surface of the cages were treated but the mosquitos were averse to settling on the floor, window, etc., which constituted a large part (28 per cent.) of the untreated area.Limewashes containing 160 mg. DDT per square foot gave a high kill of mosquitos after two hours' exposure in the cage; and 8 mg. per square foot of the active principle of “Gammexane” gave a high kill with a one hour exposure.Both treatments remained effective for 6–8 weeks under temperate conditions.