Ada County Weed Pest and Mosquito Abatement Mosquitoes of Ada County

 

There are approximately 3,000 species and sub-species of mosquitoes found around the globe. Just 14 are common to Ada County, and among those, only six are of major concern as nuisance or vector (ability to transmit disease) mosquitoes. In the chart below, we've compared these mosquitoes including which carry the West Nile virus and their habitat. Click on the mosquito genus name to learn more. You can also learn more about the insects most commonly misidentified as mosquitoes.

Genus	Type	Habitat	Activity	Overwinter Stage	West Nile Vector?	Other
Aedes	Flood	Flooded pastures, fields	Feed in shade during the day, extremely active at dusk	Egg	No	Fierce biters, great abundance in swarms, large dispersal
Culex	Pond	Standing water, containers wheelbarrows, buckets, tires, birdbaths, water- troughs, roadside water, stormdrains, catch basins	Dusk to midnight and dawn	Adult	Yes	Some species prefer avian blood meals in early spring, but later turn to mammals and human blood meals
Ochlerotatus	Flood	Flooded pastures, fields, marshes, treeholes, snowmelt, agriculture, some species breed in artificial containers	Shaded locations and daytime to dusk	Egg	No	Vicious, painful biters, produce in large numbers
Anopheles	Pond	Marshes, standing water- abundance of algae preferred	Dusk to dawn	Adult	No - Malaria	One of the first biters in spring; readily enters houses
Culiseta	Pond	Standing water, poorly drained irrigated areas, sunlight to partially shaded pools	Dusk	Adult	No	Large mosquito species; one of the first to appear in spring. Timid feeders - prefer large mammals

Insects commonly misidentified as mosquitoes:

Crane Flies (Tipulidae)
Crane flies are larger than mosquitoes and have delicate limbs. They are commonly called "mosquito hawks," but they do not eat mosquitoes. Crane flies do not bite people. They fly very poorly and are attracted to outdoor lights including porch lights.

Chromid Midge (Chironomidae)
Midges are the most widespread insects that look like mosquitoes. Unlike mosquitoes, however, the species' body is longer than its wings. (Mosquitoes have wings that are just as long or longer than its body.) Midges can be larger than mosquitoes, but most are about the same size. Adult midges commonly fly in swarms or "clouds."

Fungus Gnats (Sciaridae)
Fungus gnats have spiny legs and are about the same size as mosquitoes. They have no proboscis so they cannot bite. The species requires a humid environment, and are usually found around potted plants or flower boxes containing damp soil.

 

About Mosquito Species Found in Ada County:

Aedes Vexans (Inland Floodwater Mosquito)
This is the most important floodwater mosquito in Idaho. Breeding sites produce great numbers of these fierce biters and because of their dispersal range, their influence can be felt over a large area. Winter is passed in the egg stage and there are generally one or more broods per season, but not all eggs hatch with a single flooding. Therefore irrigation practices with poor drainage suit this species well. Females prefer feeding in the shade during the day and are extremely active at dusk. This mosquito is capable of transmitting Western Equine and St. Louis encephalitis viruses.

Ochlerotatus Sticticus (Floodwater Mosquito)
As the common name implies, this is an important floodwater species found throughout Idaho. It breeds in large numbers in floodwater pools in the bushy bottomlands along rivers. It is a single-brooded species and eggs have been known to survive (in the absence of flooding) for at least three seasons. Females are strong fliers and disperse many miles from the breeding area. It is a serious pest to shaded areas during daylight hours and at dusk and dawn. They readily enter dwellings to obtain a blood meal. The species overwinters in the egg stage. This mosquito is capable of transmitting Western Equine and St. Louis encephalitis viruses.

Ochlerotatus Dorsalis (Salt Marsh Mosquito)
This is an important pasture and field mosquito in Idaho. It is a vicious biter and is often a source of complaints many miles from the breeding site. The larva of this species occurs in a great variety of habitats including both fresh and strongly alkaline water. Habitats associated with irrigation produce large populations of this species since temporary grassy pools exposed to direct sunlight are a preferred larval habitat. As many as 10 successive broods in a single season may be common. This species is a very strong flier and migrates many miles from the breeding site; as far as 22 miles have been reported in Utah. Natural infection Western Equine and St. Louis encephalitis viruses have been reported for this species.

Culex Pipiens (Northern House Mosquito)
Because of its close association with human habitation, this nondescript mosquito is considered domesticated. It is common throughout the state. In mature communities with an overgrowth of vegetation, the species can be very abundant. Its multi-brooded eggs are laid in rafts in temporary and permanent pools, retention ponds, open septic tanks and in numerous artificial containers (that can be found around people’s homes). Breeding water with a high organic content is preferred. In numerous catch basins in one densely populated community of Ada County, as many as 300 to 1,200 larvae per square foot were found This mosquito does not migrate far from its breeding area and females overwinter. Feeding begins shortly after sunset and most feeding is completed by midnight. Although birds are the host of choice, feeding on humans in Idaho has been reported. Culex Pipiens is a vector of western equine and St. Luis encephalitis viruses as well as organisms of a number of animal diseases. Recently, the species has been listed as the primary vector of the West Nile virus in the eastern United States, and has been found to transmit this virus among birds in urban settings in the west.

Culex Tarsalis (Western Encephalitis Mosquito)
This is a common, pestiferous and important mosquito of Idaho. According to research reported in 2002, this species has the greatest potential to amplify and maintain the West Nile virus and may be the principal “bridge vector” (passing a disease outside its usual cycle to other susceptible hosts) in rural and agricultural ecosystems. It is considered to be the most adaptable of any of the Culex species in the Western states. This species is found throughout the state to an elevation of 9,000 feet. Unfed females overwinter in protected places such as cellars, outbuildings, culverts, rock piles, animal burrows and other sheltered locations. Upon emerging, the female seeks a blood meal to mature her eggs. Preferred breeding sites include open, sunlit temporary (or semi-temporary) bodies of fresh or polluted water, marshes, waste irrigation water, ditches , retention ponds and even artificial containers in rural and urban areas. Several broods are produced per season. Flight dispersal distance from breeding sites has been reported at up to 15 miles. Females are persistent biters and under ideal climatic conditions become active 30 minutes after sunset until sunrise – though most only feed for an hour after the sun sets. Although females prefer avian blood in the spring, they later turn to mammals and humans as a source of blood. This habit makes this mosquito a very important bridge vector. This mosquito is the most important vector of western equine and St. Louis encephalitis viruses.

Anopheles Freeborni (Western Malaria Mosquito)
This is the most common and abundant anopheline mosquito in Idaho. The suspected malaria outbreak in Horseshoe Bend in the late 1930s is attributed to this species. The female overwinters in sheltered locations and emerges in the early spring. The species is one of the first biters of the season, attacking when the air is still cold. They bite freely from dusk to dawn. Females readily enter dwellings and feed on humans. Eggs are commonly laid singly in semi-permanent water sources associated with poor irrigation practices. This mosquito is known to be a malaria vector. 

Culiseta Inornata (Winter Marsh Mosquito)
This large mosquito is abundant in Idaho and is commonly associated with poor irrigation practices. Females generally overwinter and emerge even before snow has disappeared. Larvae collected in the winter under ice suggests that this species may pass the winter in this stage also. Females lay eggs in rafts on the water surface of a variety of permanent and semi-permanent sunlit or partially shaded pools supporting adequate mosquitoes. The species is often found in habitats with the two aforementioned mosquito species, Culex Tarsalis and Anopheles Freeborni Although females bite humans they are not persistent biters; they prefer large mammals. Females have been found with natural infections of the California encephalitis virus. The species is a laboratory-confirmed vector of western equine and St. Luis encephalitis viruses.

Coquillettidia Perturbans (Cattail Mosquito)
The aquatic stage of this uncommon Idaho mosquito is unique. Larvae attach themselves to underwater parts of emergent vegetation and obtain oxygen through the plant tissue. They do not need to come to the surface to respire. Eggs are laid in rafts on the water surface of permanent water in ponds, marshes, and log ponds containing emergent vegetation. It is expected that the species has no more than one brood a season. Females are aggressive biters, but in most areas they are not numerous enough to be a significant pest. Overwintering is the aquatic stage. 
 

 

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Ada County Weed Pest and Mosquito Abatement Mosquitoes of Ada County

 

There are approximately 3,000 species and sub-species of mosquitoes found around the globe. Just 14 are common to Ada County, and among those, only six are of major concern as nuisance or vector (ability to transmit disease) mosquitoes. In the chart below, we've compared these mosquitoes including which carry the West Nile virus and their habitat. Click on the mosquito genus name to learn more. You can also learn more about the insects most commonly misidentified as mosquitoes.

Genus	Type	Habitat	Activity	Overwinter Stage	West Nile Vector?	Other
Aedes	Flood	Flooded pastures, fields	Feed in shade during the day, extremely active at dusk	Egg	No	Fierce biters, great abundance in swarms, large dispersal
Culex	Pond	Standing water, containers wheelbarrows, buckets, tires, birdbaths, water- troughs, roadside water, stormdrains, catch basins	Dusk to midnight and dawn	Adult	Yes	Some species prefer avian blood meals in early spring, but later turn to mammals and human blood meals
Ochlerotatus	Flood	Flooded pastures, fields, marshes, treeholes, snowmelt, agriculture, some species breed in artificial containers	Shaded locations and daytime to dusk	Egg	No	Vicious, painful biters, produce in large numbers
Anopheles	Pond	Marshes, standing water- abundance of algae preferred	Dusk to dawn	Adult	No - Malaria	One of the first biters in spring; readily enters houses
Culiseta	Pond	Standing water, poorly drained irrigated areas, sunlight to partially shaded pools	Dusk	Adult	No	Large mosquito species; one of the first to appear in spring. Timid feeders - prefer large mammals

Insects commonly misidentified as mosquitoes:

Crane Flies (Tipulidae)
Crane flies are larger than mosquitoes and have delicate limbs. They are commonly called "mosquito hawks," but they do not eat mosquitoes. Crane flies do not bite people. They fly very poorly and are attracted to outdoor lights including porch lights.

Chromid Midge (Chironomidae)
Midges are the most widespread insects that look like mosquitoes. Unlike mosquitoes, however, the species' body is longer than its wings. (Mosquitoes have wings that are just as long or longer than its body.) Midges can be larger than mosquitoes, but most are about the same size. Adult midges commonly fly in swarms or "clouds."

Fungus Gnats (Sciaridae)
Fungus gnats have spiny legs and are about the same size as mosquitoes. They have no proboscis so they cannot bite. The species requires a humid environment, and are usually found around potted plants or flower boxes containing damp soil.

 

About Mosquito Species Found in Ada County:

Aedes Vexans (Inland Floodwater Mosquito)
This is the most important floodwater mosquito in Idaho. Breeding sites produce great numbers of these fierce biters and because of their dispersal range, their influence can be felt over a large area. Winter is passed in the egg stage and there are generally one or more broods per season, but not all eggs hatch with a single flooding. Therefore irrigation practices with poor drainage suit this species well. Females prefer feeding in the shade during the day and are extremely active at dusk. This mosquito is capable of transmitting Western Equine and St. Louis encephalitis viruses.

Ochlerotatus Sticticus (Floodwater Mosquito)
As the common name implies, this is an important floodwater species found throughout Idaho. It breeds in large numbers in floodwater pools in the bushy bottomlands along rivers. It is a single-brooded species and eggs have been known to survive (in the absence of flooding) for at least three seasons. Females are strong fliers and disperse many miles from the breeding area. It is a serious pest to shaded areas during daylight hours and at dusk and dawn. They readily enter dwellings to obtain a blood meal. The species overwinters in the egg stage. This mosquito is capable of transmitting Western Equine and St. Louis encephalitis viruses.

Ochlerotatus Dorsalis (Salt Marsh Mosquito)
This is an important pasture and field mosquito in Idaho. It is a vicious biter and is often a source of complaints many miles from the breeding site. The larva of this species occurs in a great variety of habitats including both fresh and strongly alkaline water. Habitats associated with irrigation produce large populations of this species since temporary grassy pools exposed to direct sunlight are a preferred larval habitat. As many as 10 successive broods in a single season may be common. This species is a very strong flier and migrates many miles from the breeding site; as far as 22 miles have been reported in Utah. Natural infection Western Equine and St. Louis encephalitis viruses have been reported for this species.

Culex Pipiens (Northern House Mosquito)
Because of its close association with human habitation, this nondescript mosquito is considered domesticated. It is common throughout the state. In mature communities with an overgrowth of vegetation, the species can be very abundant. Its multi-brooded eggs are laid in rafts in temporary and permanent pools, retention ponds, open septic tanks and in numerous artificial containers (that can be found around people’s homes). Breeding water with a high organic content is preferred. In numerous catch basins in one densely populated community of Ada County, as many as 300 to 1,200 larvae per square foot were found This mosquito does not migrate far from its breeding area and females overwinter. Feeding begins shortly after sunset and most feeding is completed by midnight. Although birds are the host of choice, feeding on humans in Idaho has been reported. Culex Pipiens is a vector of western equine and St. Luis encephalitis viruses as well as organisms of a number of animal diseases. Recently, the species has been listed as the primary vector of the West Nile virus in the eastern United States, and has been found to transmit this virus among birds in urban settings in the west.

Culex Tarsalis (Western Encephalitis Mosquito)
This is a common, pestiferous and important mosquito of Idaho. According to research reported in 2002, this species has the greatest potential to amplify and maintain the West Nile virus and may be the principal “bridge vector” (passing a disease outside its usual cycle to other susceptible hosts) in rural and agricultural ecosystems. It is considered to be the most adaptable of any of the Culex species in the Western states. This species is found throughout the state to an elevation of 9,000 feet. Unfed females overwinter in protected places such as cellars, outbuildings, culverts, rock piles, animal burrows and other sheltered locations. Upon emerging, the female seeks a blood meal to mature her eggs. Preferred breeding sites include open, sunlit temporary (or semi-temporary) bodies of fresh or polluted water, marshes, waste irrigation water, ditches , retention ponds and even artificial containers in rural and urban areas. Several broods are produced per season. Flight dispersal distance from breeding sites has been reported at up to 15 miles. Females are persistent biters and under ideal climatic conditions become active 30 minutes after sunset until sunrise – though most only feed for an hour after the sun sets. Although females prefer avian blood in the spring, they later turn to mammals and humans as a source of blood. This habit makes this mosquito a very important bridge vector. This mosquito is the most important vector of western equine and St. Louis encephalitis viruses.

Anopheles Freeborni (Western Malaria Mosquito)
This is the most common and abundant anopheline mosquito in Idaho. The suspected malaria outbreak in Horseshoe Bend in the late 1930s is attributed to this species. The female overwinters in sheltered locations and emerges in the early spring. The species is one of the first biters of the season, attacking when the air is still cold. They bite freely from dusk to dawn. Females readily enter dwellings and feed on humans. Eggs are commonly laid singly in semi-permanent water sources associated with poor irrigation practices. This mosquito is known to be a malaria vector. 

Culiseta Inornata (Winter Marsh Mosquito)
This large mosquito is abundant in Idaho and is commonly associated with poor irrigation practices. Females generally overwinter and emerge even before snow has disappeared. Larvae collected in the winter under ice suggests that this species may pass the winter in this stage also. Females lay eggs in rafts on the water surface of a variety of permanent and semi-permanent sunlit or partially shaded pools supporting adequate mosquitoes. The species is often found in habitats with the two aforementioned mosquito species, Culex Tarsalis and Anopheles Freeborni Although females bite humans they are not persistent biters; they prefer large mammals. Females have been found with natural infections of the California encephalitis virus. The species is a laboratory-confirmed vector of western equine and St. Luis encephalitis viruses.

Coquillettidia Perturbans (Cattail Mosquito)
The aquatic stage of this uncommon Idaho mosquito is unique. Larvae attach themselves to underwater parts of emergent vegetation and obtain oxygen through the plant tissue. They do not need to come to the surface to respire. Eggs are laid in rafts on the water surface of permanent water in ponds, marshes, and log ponds containing emergent vegetation. It is expected that the species has no more than one brood a season. Females are aggressive biters, but in most areas they are not numerous enough to be a significant pest. Overwintering is the aquatic stage. 
 

 

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