Blackflies can most conveniently be caught when searching for a blood-host (hungy female flies), or, less easily, when searching for a oviposition site (gravid females only) or when searching for a partner (un-mated male or female flies). It is very difficult so locate adult flies at their resting sites in the vegetation.
With view to the vectorial efficiency of a given Simulium damnosum population, it is important to assess its degree of ‘zoophily’ or ‘anthropophily’, i.e. to measure, by direct comparison, the propensity of female flies to fed on animals (cattle, birds, game animals) or man (depending on his clothing, behaviour etc.).
Although the exposure of a human bait, the ‘vector collector’ continues to be the golden standard to measure Daily, Monthly and Annual Biting rates. In Cameroon, we carried out a number of studies and tried various methods to collect hungry, ovipositing and mating flies.
Human bait: ‘Fly-collectors’
The standard method to assess the size of a Simulium vector population is to expose a human bait, the ‘fly-collector’, at a given site near the river close to a Simulium breeding site. Here he exposes his legs below the knees and catches all Simulium flies that come to land on his legs during one day from dusk to down (6 to 18.30 hrs).
Automatic fly trap: “The magic fly-boy”
Automatic trap for boophilic flies: “The magic cow”
Tent-trap for studying attraction of human and animal baits: “The magic tent”
A bait (chicken or man) is placed under a tent, which is open at the bottom (ca. 10 cm) so that only the smell of the bait can be attractive, whilst the bait itself is hidden, and can not be recognized by the blood-hungy flies, until the have entered the tent. The flies attracted are caught in a mosquito-wire on the uper edge of the tent. In a variation, the tent can be raised, so that the bait becomes visible and the numbers of flies attacted (per 5 minutes9 can be compared for the bait being visible or hidden.