Species: Aedes nigromaculis


This species readily attacks man and domestic animals. It is a suspected vector of WEE.


This species occurs throughout the western 2/3rds of the US. In the Central Valley of California, it is a major pest species. In Montana this species usually represents 1% or less of collections. One exception is trap sites along the Hi-Line, especially Valley County, where this species is more abundant. Up to 150 eggs may be deposited per female. They are laid at the edge of drying pools, mostly among grass lumps near the base of the grass stems. In mid-summer this species can complete immature development in 5 – 7 days. Host-seeking activity is primarily crepuscular with peaks in the evening and morning. Females feed predominantly on large domestic animals and humans. In irrigated pastures adult females remain near the point of emergence for a few days as long as moisture and food are available. When these factors change, movement toward populated centers may take place. This species has a wide dispersal range of 20 to 30 miles.

Identifying Characteristics:

Pointed abdomen, dark body, pale leg bands wide and only on basal side of leg joint, may have pale band on proboscis, longitudinal stripe down abdomen.

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)