Culicoides variipennis is a 1 millimetre (0.039 in) long biting midge. It is a part of the subgenus Monoculicoides and has many subspecies. Found in North America, C. variipennis transmits Bluetongue virus, African horse sickness virus, akabane virus, and epizootic hemorrhagic disease.
The C. variipennis is less than 1 millimetre (0.039 in) long, which makes it difficult to keep from livestock. The wings of C. variipennis are spotted and narrow with few veins; the wings fold over the abdomen while the C. variipennis is at rest. The max flight range for male C. variipennis is 0.8 kilometres (0.50 mi) and for females 4.0 kilometres (2.5 mi), while the mean flight range is 1.89 kilometres (1.17 mi). Flight activity is dependent on the light intensity and temperature; most flight, and thus most bites, occur around dawn and dusk. A distinction between male and female C. variipennis is that females have different mouthparts that allow them to blood feed.
The life cycle of the C. variipennis is from half a year to three years. The larva, found typically near sewage tank outlets or stock tanks where manure is trampled into the soil, are slender, transparent to orange colored worm-like and lasts 15–23 days of larval stage. The aquatic/sub aquatic larvae feed on dying organisms or other organic material.
The C. variipennis and the five subspecies, C. v. variipennis, C. v. sonorensis, C. v. occidentalis, C. v. australis, and C. v. albertensis, are found in various locations of the United States. The C. v. variipennis is found in the north east United States, but is not a vector for Bluetongue virus in this area because of low susceptibility; the C. v. sonorensis is found from Florida to California, north to Virginia and Ohio, and in the west from Washington to British Columbia, but they leave Colorado in the winter; the C. v. occidentalis is found in Arizona to California and from Washington to British Columbia.