[1] The C. v. australis and C. v. albertensis have difficulty in defining the subspecies relationship and together make up the C. variipennis complex.
[1] Female C. variipennis show slender to slightly swollen third palpal segments with sensory pits that are shallow round and small as opposed to males[4] Distinction against the subspecies C. v. sonorensis and C. v. occidentalis show that the females are identical morphologically with the enlarged third palpal segment with their sensory pit being a rounded, medium to large size[4] For the male difference of C. v. variipennis, C. v. occidentalis and C. v. sonorensis, on the ventral surface of aedeagus, C. v. variipennis and C. v. occidentalis lack spicules, while male C. v. sonorensis have many prominent spicules on the aedeagus.
[4] The C. variipennis attacks in swarms with the Bluetongue virus; this can be devastating to livestock and is the most economically important arthropod borne animal diseases in the United States.
[1] The C. variipennis can transmit diseases if the population density is greater than one per 3.57 km2; however, this can be reduced if the area is treated with insecticide.
[2][5] When infected with Bluetongue virus, cattle experience similar symptoms such as abortion and stillborn calves, but it is often less severe compared to sheep.
[1] Both poor nutrition as a larva and more quantity in blood meal means a higher likelihood of being infected.
This parasitism of H. magnapapula and C. variipennis is commonly found in the Chino Basin in California Riverside County and the Allegheny, Thompson and Cayuga areas of New York.