The diel, seasonal, and lunar host-seeking periodicity of Culicoides mississippiensis, C. floridensis, C. barbosai, and C. furens was studied near Yankeetown, Florida. Culicoides mississippiensis was the only species active during all seasons. Significantly more (P less than 0.05) individuals sought a blood meal when the moon was full than when the moon was in some other phase. Culicoides floridensis, the species with the shortest wing length, did not attack when the wind speed exceeded 9 km/h, and C. mississippiensis, the species with the greatest wing length, did not attack when the wind speed exceeded 17 km/h.