West Nile Virus

Mosquito Species

There are more than two thousand five hundred species of mosquitoes around the world. About two hundred of these different species can be found in the U.S. and Canada. Forty-three of these species can carry the West Nile Virus. Some of the mosquitoes that are common carriers of West Nile Virus are the following.

Culex Pipiens - They can be found in Central and Eastern United States with the exception of Florida, and in urban areas elsewhere in the U.S.A. House mosquitoes are common in urban and suburban communities as well as on rural premises. Their breeding grounds include storm sewer catch basins, clean and polluted ground pools, ditches, animal waste lagoons, effluent from sewage treatment plants and other sites that are slightly to very eutrophic or polluted with organic wastes.

Culex Quinquefasciatus- They are generally active only during the warmer months; they usually attack humans towards the middle of the night indoors and outdoors, but are often more attracted to birds. They typically lay a single batch of 140-340 eggs after each blood meal. These mosquitoes can be found in the same areas as the Culex Pipiens.

Culex Restuans - They have a distribution that ranges from Central Canada south into Mexico. This type of mosquito is very common in the eastern and Central United States. Pregnant females enter hibernation in fall and hibernate in basements, spring houses, outbuildings and subterranean enclosures during the winter months. They thrive on moisture and a humid atmosphere. In April they begin to lay their eggs and can be found mainly in southern New Jersey. By May they move further north and have reached their peak population by July. They breed in temporary ground water, the edges of grassy swampland, sphagnum bogs, road side ditches, tire ruts, hoof prints, discarded buckets, tires, catch basins, sewage effluent and septic seepage.

Aedes Albopictus - The "Asian Tiger" mosquito was first discovered in Houston Texas in 1987. It has spread to 678 counties in 25 states. Such mosquitoes carry over twenty two arboviruses, including many viruses of public health importance. This mosquito is widely distributed in the South-Eastern United States. Its eggs can survive very cold winters resulting in their potential to carry diseases into a substantial portion of the United States. Infestations are less common northward and westward, presumably because of less hospitable environments.

Aedes Vexans - are one of the most widespread mosquito species in the world. Their distribution includes Nearctic and Palearctic regions, the African west coast as well as Oriental regions. In North America, they are common in Southern Canada and throughout the United States with the exception of Hawaii. They lay their eggs in small depressions which are subject to flooding. The females are persistent biters and most active in the early evening. The adults are known to fly great distances and are readily attracted to light.

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