In a search for the forest vector of yellow fever, catches of biting Diptera have been made by various methods in forest trees in Bwamba County, Uganda. The work here reported concerns Tabanids taken in catches made during the period 1944–45.
Three species of Tabanids have been taken in trees during these catches, and one of these, Chrysops centurionis, has proved to be mainly arboreal.
Observations on C. centurionis have shown that its main biting-activity begins just before sunset and reaches a peak during the hour after sunset. Thereafter the numbers taken diminish rapidly, but some activity continues throughout the night.
In the wet-season catches, this species was most prevalent in the forest canopy at heights of 50 to 60 feet above ground. In the dry season the most favourable level was lower, at 20 to 30 feet above ground.
It is suggested that monkeys are the natural hosts of C. centurionis, and that C. centurionis may be the vector of filarial infections among wild monkeys.
It is shown that there is a very close correspondence between the biting-behaviour of C. centurionis and that of the mosquito, A ëdes africanus.
Evidence of nocturnal activity has now been obtained in the case of one species of Tdbanus, three species of Haematopota and two species of Chrysops. It is suggested that there may be some connection between the remarkable eye colours of Tabanids and crepuscular or nocturnal activity.
Records of other Bwamba Tabanids are given.