The direction of flight of mosquitoes (Diptera, Culicidae) near the ground in West African savanna in relation to wind direction, in the presence and absence of bait

The direction of mosquito flight near the ground, in relation to wind direction, was investigated at Keneba in The Gambia, West Africa. Directional flight traps facing eight directions sampled mosquitoes flying between ground level and 1·4 m, and unbaited and baited catches with a calf at the centre of the trap circle were performed. Data on non-host-oriented flight were obtained for unfed femaleAnopheles melas(Theo.),Culex thalassiusTheo. andC. tritaeniorhynchusGiles from the unbaited catches, and from all catches of unfed females of theC. deceitsgroup, and gravid and male mosquitoes, which did not respond to the calf. The baited catches included large numbers ofA. melas, C. thalassiusandC. tritaeniorhynchus, and fewerAnopheles squamosusTheo. andA. ziemanniGrünb. In both unbaited and baited situations, flight appeared to be in a predominantly upwind direction, although mere was some indication, in the presence of a calf, of convergence into the host stream.