Culicoides variipennis (Diptera:Ceratopogonidae) host selection in Colorado.

Drop traps containing either steer or ewe bait were used to investigate host selection and crepuscular period host seeking activity of Culicoides spp. at 2 farms in Colorado. Of the 1,103 Culicoides spp. collected, 755 were Culicoides variipennis (Coquillett). Of these, 86% were collected from steers and 14% from ewes. The engorgement rate of C. variipennis was 31% on steers and 6% on ewes. Culicoides crepuscularis Malloch was the 2nd most abundant species. Of the 253 collected, 39% were from the steers, and 61% were from ewes: The engorgement rate of the C. crepuscularis collected was 71% on ewes and 34% on steers. Thus, C. variipennis preferentially selected and fed upon cattle, whereas C. crepuscularis preferentially selected and fed upon sheep.