Abstract
In order to evaluate the blackfly control, the comparison was made for the efficacy of the CO_2-traps with 2kg of dry ice or with the different discharge rates of CO_2 gas (250,500,1,000,2,000ml/min). Mini-CO_2-traps with 1kg dry ice operated by battery were also tested for the collection of the blackfly, Simulium ochraceum, in the endemic area of onchocerciasis in Guatemala. The species composition of adults collected with the CO_2-traps was similar to that of larvae from the nearby breeding place. The number of blackflies collected by the CO_2-traps varied greatly with discharge rates of CO_2 gas. Seasonal trends of blackfly density obtained by the CO_2-traps at the rates of 1,000 and 2,000ml/min and dry ice were similar to each other. But the traps with less than 500ml CO_2/min didn't produce satisfactory results to demonstrate the trends. The species composition by the mini-CO_2-trap was similar to that by a human bait catch, but the number of blackflies by the former was less than one tenth of that by the latter.
