Simulium ochraceum females collected after feeding on subjects harboring Onchocerca volvulus were maintained and transported from Guatemala to California in small plastic tubes. Each tube had a perforated cap for entry of air, a wick as a reservoir for the nutrient solution (30% sucrose), a strip of filter paper for anchorage, and contained one fly. The tubes were kept in plastic boxes which, in turn, were maintained in portable coolers. Direct sunlight, heat and mechanical trauma easily killed the flies; moreover, loss of flies was also due to oversaturated wicks, high humidity in the plastic boxes, and loose tube caps. Approximately 70% of the captured flies could survive an 8-day period of captivity, and approximately 40% were still alive 11 days after capture.