A latex agglutination test to identify the sources of blood-meals of Culicoides is described. The method requires the minimum amounts of reagents and apparatus and would be suitable for rapid tests under field conditions. Blood-meals of Culicoides nubeculosus (Mg.) and C. variipennis (Coq.) from laboratory cultures, which had engorged on blood from several species of domestic animals, were differentiated without difficulty. In a series of ‘blind’ tests, the blood-meals of 49 C. variipennis from seven species of domestic animal were identified with 100% accuracy. The differentiation of blood-meals from closely related hosts, such as mouse and guineapig or ox and sheep, is entirely dependent upon the specificity of the antisera conjugated to the latex. Blood-meals could be identified reliably for about 48 h after ingestion at 20–25°C, but at higher temperatures the reaction became less reliable after 24 h. Detergents commonly used in collecting midges had no effect on the latex agglutination test, but 0–01% mertbiolate, often used as a preservative, caused auto-agglutination and cannot be used when this test is to be applied.