A large pond, up to 2000 m2 area, adjacent to the sea at Jimbo, near Vanga, on the south coast of Kenya was studied for salinity and the presence of mosquito larvae 1980–1981. Rainfall peaked in November–December 1980 and again in March–May 1981, while salinity of the pond-water fluctuated inversely from dryness in February, more than 100% seawater equivalent in months before main rains, to below 13% seawater after the onset of rain in March.
Five types of mosquito larvae occurred in the pond: Aedes albocephalus mostly at 21–30% salinity (range 13–30%); Culex sitiens mostly at 31–40% salinity (range 13–54%); Culex tritaeniorhynchus and Culex thalassius mostly at 41–50% salinity (range 13–50%) and the Anopheles gambiae complex from 13 to 54% salinity, at least those at higher salinities being Anopheles merus. No larvae were present when salinity surpassed 54% through evaporation, or fell below 13% after rain. The most reliable way to limit or control these pest and vector mosquitoes at Jimbo would be to drain the pond into the sea after rainfall, so that mosquito populations could not increase by breeding sequentially, while salination proceeds.