Mosquitoes of Santa Barbara County
Mosquitoes grow in stages - eggs, larvae, pupae and adults. The larvae look significantly different than the winged adult. The pupal stage is the stage between the larva and adult, where the mosquito grows wings and transforms into the adult. The process is called metamorphosis.
Mosquito larvae and pupae live and grow in water. Adult mosquitoes are the winged breeding stage that live out of the water.
Mosquito larvae have general characters that can identify the genus. Anopheles mosquito larvae lack breathing tubes ("siphons") and lie flat on the water surface. Other mosquito genera rest at an angle to the surface with their siphons at the surface. Mosquito pupae, also known as "tumblers", can move around but do not feed.
The black salt marsh mosquito is small to medium-sized. Although it is an aggressive biter that targets mammals, day or night, it is not a major disease vector. The Carpinteria Salt Marsh is its main larval habitat in Santa Barbara County, but adults can sometimes be found more than ten miles from their breeding grounds. The Goleta Slough is also a source of Aedes taeniorhynchus (pronounced AY-deez teen-eeo-RINK-us). Tides above six feet, during the new or full moon, leave pools of water around the inland edges of the salt marshes. These pools lay stagnant until the next tide over six feet. Eggs that have been laid on the soil hatch when immersed by the extra-high tides and when temperatures are warm enough (typically late April through October). Our technicians can be seen inspecting and treating the salt marshes a few days after each of these extra-high tides. Santa Barbara County is the northern end of their range.
Mosquitoes in the genus Aedes have abdomens that end in a point.
This medium-sized mosquito bites during the day and early dusk. Females viciously feed on large mammals and humans, and they may travel great distances, 10 to 20 miles, to do so. This species is univoltine, meaning only one generation is produced per year. The immature stages develop in brackish pools after the winter rains, along the California coast, south of Bodega Bay. The adults emerge in late winter or early spring.
The western treehole mosquito, the main vector of dog heartworm on the West Coast, is found throughout most of the state. One brood per year of larvae and pupae develop in rot holes in trees, usually oaks, that fill with rainwater. They have also been found in decorative oak wine barrels. They do not fly far from their breeding grounds. The adult females seek mammals, including man, in late winter and early spring, day and dusk. Adults are so small that they may be able to squeeze through window screen!
Another univoltine (single generation per year) species, Aedes washinoi breeds in wetlands flooded by winter rains. Eggs are laid on moist soil or vegetation as wetlands dry-up in late spring. Eggs hatch the following winter when flooded by rain. Adult females, staying within one half mile of their larval sources, are agressive day-biters that will readily feed on humans.
Although this species is capable of carrying malaria, it rarely bites humans. It is a possible vector of dog heartworm. Females bite around dusk and dawn, usually within one mile of their breeding source. Larvae and pupae can be found in shallow, sunlit pools with algae, especially on top of floating algae mats. Widespread throughout California.
The medium-sized woodland malaria mosquito is a possible vector of malaria. Adult mosquitoes bite around dusk and dawn, and they will fly about one mile from larval habitats. Larvae occur in shaded, grassy, pools.
Male mosquitoes of every genus have long palps on each side of
the proboscus. In the genus Anopheles, females do, too!
Anopheles hermsi is very capable of transmitting malaria and, to a much lesser extent, West Nile virus. Females may travel more than five miles to feed on large mammals, including humans, at dusk and dawn. Larval stages are found in freshwater pools with emergent vegetation. This species is found south of San Luis Obispo County in California.
Santa Barbara is at the southern edge of this mosquito's range in California. It can carry malaria, but it rarely bites humans and is only occasionally found in Santa Barbara County.
As its common name implies, tule mosquito larvae are found in ponds and marshes with tules and cattails. Local sources include the Andree Clark Bird Refuge, Lake Los Carneros, peripheral areas of the Goleta Slough, and the Sage Hill Campground in the upper Santa Ynez Valley. As the scientific name implies, the adult mosquito's throrax (body region between head and abdomen) is a reddish color. Adult females target bird and human hosts and are vectors of West Nile virus. They usually stay within two miles of their larval habitat.
The southern house mosquito is one of the most important vectors of West Nile virus in urban settings. Larval habitats include various polluted, urban, or residential water bodies such as storm drains, poorly maintained swimming pools, ditches, and flower pots. Rafts of eggs are deposited on the surface of the water. After emergence as medium-sized, brown adults, they stay close to their breeding habitat. Female adults seek birds and, secondarily, humans and other mammals for blood meals, mainly at night. Found south of the San Joaquin Valley.
This species is very uncommon in Santa Barbara County, but it is a capable vector of West Nile virus and other encephalitides. It is associated with agricultural settings. In the eastern United States, Culex restuans is known to be the first to colonize water in discarded tires.
Banded foul water mosquito larvae are most associated with sources high in organic content like agricultural ponds and sewage treatment ponds. They are not too abundant in Santa Barbara County. Adult females feed predominantly on birds at night, flying up to ten miles from their breeding source. They are a West Nile virus vector.
Culex tarsalis is the most widespread mosquito in California, found in all counties at elevations from below sea level to 10,000 feet. Rafts of about 190 eggs are laid in a very wide variety of water sources. In Santa Barbara County, this species is common at the Andree Clark Bird Refuge, around the Goleta Slough, and in many of the creeks. Females are night feeders that prefer birds, especially during nesting season, and mammals, including humans. They have been known to travel up to 15 miles from their breeding grounds to feed. The western encephalitis mosquito is the primary vector of West Nile virus, St. Louis encephalitis, and western equine encephalitis in California.
The cool-weather mosquito is a large species that seeks to bite large mammals and humans at night. It travels up to five miles from the shaded, clear water sources in which this species develops. Eggs are laid in rafts on the water surface. C. incidens is found throughout California, and is active in fall, winter, and spring.
With no spots or stripes on the wings or legs, Culiseta inornata is the largest mosquito in our area. It is widely distributed in California and is less active in summer. Egg rafts are laid on the surface of sunlit pools with low to moderate levels of pollution, alkalinity, and salinity. Females frequently feed on large mammals at dusk.
This large species is found along the California coast and foothills. Dark scales on the wing cross veins are an identifying feature. Egg rafts, larvae, and pupae are found in creeks, vernal pools, and catttail-filled pools. This species has never been documented as a disease vector.