Duration of larval development of Simulium yahense (Diptera: Simuliidae) under natural conditions.

The duration of Simulium yahense Vajime & Dunbar larval development on a dam spillway in Harbel, Liberia, was observed to make accurate decisions regarding the frequency of larvicide treatments against this onchocerciasis vector. Larval development required a minimum of 10-12 d from eclosion to first pupation. Initial larvicidal treatment for S. yahense control would require a treatment cycle of 7 d. Once suppression of adult and larval populations is achieved, a 9-12-9-12 day treatment cycle could be adopted.