Species: Culiseta inornata


This species has been found infected with WEE and WNV. Its low seasonal abundance and narrow host feeding pattern, primarily large mammals, suggests that it is not play a major role in transmission of these arboviruses, especially to man.


Cs. inornata occurs throughout North America and has been reported to be at elevations from sea level to 10,000 ft. In Montana, adults have been collected across the state and larvae have been collected at 7,000’ (Quickenden and Jamieson 1991). Female Cs. inornata will lay about 150-200 eggs in clusters called rafts that float on the surface of the water until the larvae hatch (about two days). Temporary or permanent pools with pockets of sunlight are preferred egg laying sites. Larvae are found in a wide variety of standing water, especially impoundments associated with wetlands and irrigation; they can tolerate cool water temperatures with moderate levels of alkalinity or organic pollution. Under optimum conditions, development from egg to adult can take a minimum of 10 - 14 days depending on water temperature. Females are active fliers and can disperse 5 - 10 miles from their emergence site. Because females seem to prefer feeding on large mammals, they can be troublesome to livestock. Analyses of blood from engorged Cs. inornata collected from Medicine Lake (Sheridan County, Mont.) showed the majority had fed on cattle (Friesen and Johnson 2013). Adults of this species are active during cool weather when few other night-flying insects are active. This species overwinters as adults.

Identifying Characteristics:

Rounded abdomen, base of wing vein Sc with row of setae ventrally, hindtarsomeres not banded, wing with dark and pale scales intermixed on anterior veins.

Distribution Map:

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Mosquito and Vector Surveillance Program

MSU Extension - Department of Animal and Range Sciences

Montana State University
P.O. Box 172900
Bozeman, MT 50717-2900

Location: Marsh Labs, Room 59

Veterinary Entomology Research Associate:

Marni Rolston

Professor Emeritus of Veterinary Entomology:

Dr. Greg Johnson


Dr. Grant Hokit (Carroll College)