The host-preferences of a number of South African Culicoides biting midges were determined by precipitin tests and by an analysis of catches from light traps set near host animals. Results showed C. pallidipennis to feed predominantly on cattle and horses and possibly sheep, C. schultzei mainly on cattle, C. distinctipennis only on birds (possibly poultry), C. pycnostictus chiefly on birds, and C. milnei mostly on horses. A further five species gave positive precipitin test reactions to blood of either cattle, horses or birds but too few specimens were available for the significance of these reactions to be evaluated. These results suggest that C. pallidipennis and C. schultzei might be involved in the transmission of cattle diseases, C. pallidipennis and C. milnei of horse diseases,
C. distinctipennis and C. pycnostictus of poultry diseases and C. pallidipennis of sheep diseases.