Assessment of a silhouette trap for sampling zoophilic blackflies (Diptera: Simuliidae)

A collapsible animal-type silhouette trap was designed to catch zoophilic female blackflies (Diptera: Simuliidae) which feed on the head or ventral surface of cattle. The trap was assessed for its ability to sample attacking blackflies by comparison with simultaneous manual catches from a bait cow, in an enzootic bovine onchocerciasis area in North Wales. In thirteen 1-hour collections, the trap provided a representative sample of the blackfly population in terms of the relative abundance of species. There was a strong correlation between the catch sizes from both methods (r = +0.73), and the body site feeding preferences for all species were similar with both trap and cow. There was no significant difference between the Onchocerca spp. infection rates of flies caught by either method.