Abstract
Culicoides nubeculosus, the vector of Onchocerca cervicalis, was found to have two daily peaks of activity when attacking horses in South Hertfordshire. The evening peak occurred just before sunset and was 2–2.5 times as great as the morning peak. Most of the attacking midges (85 %) landed on the ventral mid-line of the horse in an area stretching from the front legs to the sheath or mammae. The attractiveness of the ventral surface of the host was found to be related to illumination and to the arrangement of the host's body hair. 42.1 % of the C. nubeculosus landing on the host were successful in obtaining a blood meal.