Observations on the biting habits of mosquitos in the forest canopy at Zika, Uganda, with special reference to the crepuscular periods

Publisher Website
Google Scholar
Abstract
The results of sixty 24-hour catches of mosquitos carried out with man as bait in the forest canopy at Zika, central Uganda, are discussed. In these catches the arrival of mosquitos was recorded to the nearest minute.The rapid changes of light intensity in the equatorial twilight are discussed in relation to a series of readings made at Entebbe.It is shown that among species that show a crepuscular peak of biting activity (Aedes ingrami Edw., A. africanus (Theo.), Mansonia fuscopennata (Theo.) and M. aurites (Theo.)) the peaks do not all occur at the same time, but form a succession.Moonlight (at least in the forest canopy) has no apparent effect on the timing of these crepuscular surges of biting activity.One species (M. fuscopennata) also shows a peak of biting activity before sunrise. This peak is closer to sunrise than the evening peak is to sunset. A brief reference to current work carried out above the canopy, where foliage, shadows, etc., do not complicate the environment, shows that this phenomenon occurs in other species also. It is concluded that in these species the morning peak must almost certainly occur in light of much greater intensity than the evening peak.The implications of these findings are discussed with reference to the questions of endogenous rhythm and exogenous stimuli.