Response of two African simuliids to silhouettes and carbon dioxide.

Simulium adersi Pomeroy and a species close to S. impukane de Meillon were attracted to and landed on silhouettes at ground level when 100–200 ml of carbon dioxide per min. were released beside them. More flies landed on the lee and shady portions of the silhouettes than on the windward and sunny sides. No flies landed on the silhouettes without the carbon dioxide.