Aedes squamiger

Aedes squamiger, commonly known as the winter salt marsh mosquito or California salt marsh mosquito, is a species of mosquito native to the west coast of the United States and Baja California, Mexico. It is recognized for its aggressive daytime biting behavior and its role as a potential vector for the California encephalitis-like virus, although it is not considered a major human disease vector.

Aedes squamiger
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Diptera
Family:	Culicidae
Genus:	Aedes
Subgenus:	Ochlerotatus
Species:	A. squamiger
Binomial name
Aedes squamiger (Coquillett, 1902)

Taxonomy

Aedes squamiger belongs to the genus Aedes within the subgenus Ochlerotatus. It was first described by entomologist Daniel William Coquillett in 1902 based on specimens collected from Palo Alto, California.^[1] It is closely related to Aedes hexodontus and has one known synonym, Grabhamia deniedmannii Ludlow, noted from Benicia, California.^[2]

Description

The proboscis features a mix of dark and pale scales without a median pale band. Its legs have broad basal pale bands on the tarsi, with the pale band on the second tarsal segment of the hind leg being less than one-third of the segment's length. The scutum displays mixed brown and pale scales laterally, while the postpronotum lacks contrasting scale patches. The wings are covered with broad, triangular-shaped dark and pale scales evenly intermixed, and the tertiary fringe scales are a mix of black and white. The abdomen has basal pale bands on the terga.^[2]

Distribution

Aedes squamiger is distributed along the west coast of the United States, from Bodega Bay in Sonoma County, California, southward into Baja California, Mexico.^[2] This coastal species is commonly found in pickle weed tidal and diked marshes.^[3] Its breeding sites include salt marsh pools diluted by winter and early spring rains, cracked ground in diked wetlands, and old dredge disposal sites.^[3]

Behavior

Aedes squamiger exhibits aggressive daytime biting behavior. It overwinters as drought-resistant eggs, which hatch in early winter when water temperatures drop below 10 °C (50 °F). Adults emerge in large numbers in spring, with females capable of traveling dozens of kilometers inland to seek blood meals.^[2] It is a significant pest during spring, though it is not frequently captured in CO₂-baited traps.^[2]

Ecology

Its life cycle is adapted to coastal environments, with eggs hatching in early winter and larvae developing slowly through the winter in cold, highly oxygenated water.^[2]

Medical significance

Aedes squamiger can carry a California encephalitis-like virus, a bunyavirus capable of causing encephalitis in humans. This virus was first isolated from adults reared from larvae collected in January 1989 at Morro Bay, San Luis Obispo County, California.^[4] Despite this, there are no well-documented cases of human disease transmission by this species, and it is not regarded as a primary vector for major human diseases.^[3]