Changes in Mosquito Flight Associated With Natural Changes in Polarized Light

Diurnal activity of Aedes and Culex spp. was observed near Banff, Alta., and Hope, B.C., when naturally polarized light was present, reduced, or absent in relatively open habitats. Resting mosquitoes attacked as soon as they were approached closely, whether or not polarized light was present. In contrast, mosquitoes made long, roving flights only when there was polarized light overhead. Roving flight stopped whenever zenith polarization was disrupted by passing clouds or by the unpolarized glare surrounding the sun. As overhead polarization is most intense near sunrise and sunset, it could be employed then by mosquitoes travelling to and from feeding or oviposition sites.