Deet, (N,N-Diethyl-m-toluamide), treated wide-mesh knotted cotton netting was evaluated for its repellent effectiveness against mixed field populations of mosquitoes, biting midges (Culicoides spp.) and Phlebotomine sand flies during the rainy season in the Panama Canal Zone. Such netting proved effective against hematophagous flies for about 64 days, as determined by CDC mini-light trap collections. Results indicated that field use of bed nets made of Deet-treated wide-mesh netting should offer effective temporary protection even under humid conditions.