A method for distinguishing parous from nulliparous Ceratopogonidae was applied to midges of the Culicoides variipennis complex collected in CO2-bait traps in Kern County, California. To evaluate the technique, matched pools of “parous” and “nulliparous” midges were tested for viruses. Thirty-six virus isolations, representing 3 viruses (Buttonwillow, Lokern, and Main Drain), were made from pools classified as parous, whereas no isolations were made from pools considered nulliparous. Biting populations and parous rates were relatively high in the spring and in the fall. The scarcity of parous females in midwinter and other features of the winter biology of C. variipennis indicate that adult females probably do not provide for overwintering of arboviruses in Kern County.