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All Stages of Mosquitoes

Eggs, Larva, Pupa, and Adult

May contain: art, collage, animal, bee, insect, invertebrate, and wasp

There are over 3,000 mosquito species in the world, more than 50 reside in California, and 25 species are commonly found throughout Butte County. Regardless of adult mosquito populations, several species in Butte County are of public health concern including Culex tarsalis, Culex pipiens, Aedes melanimon, Aedes sierrensis, and Anopheles freeborni.

Common Name: Encephalitis Mosquito
Scientific Name:
Culex tarsalis

Culex tarsalis is the primary vector of West Nile virus (WNV), Saint Louis encephalitis (SLE), and the western equine encephalomyelitis (WEE). Culex tarsalis breeds in a variety of aquatic habitats ranging from clean to polluted water sources including, but not limited to flooded agricultural lands, ditches, man made containers, ponds, and urban sources. In Butte County, this mosquito breeds year round and prefers to feed on birds, but does readily attack humans, horses, and cattle.

Common Name: Northern House Mosquito
Scientific Name:
Culex pipiens

Culex pipiens is a major vector of West Nile virus (WNV) and can vector Saint Louis encephalitis (SLE), and the western equine encephalomyelitis (WEE). Larvae prefer polluted or foul water high in organic content. Usually found in artificial containers, storm drains, wastewater ponds, sumps, septic tanks, fountains, birdbaths, and un-maintained swimming pools. Birds are the principal blood meal, but will attack humans and invade their homes. Culex pipiens usually breed in the early spring to late fall in Butte County.

Common Name: None
Scientific Name:
Aedes melanimon

Aedes melanimon is not only a major pest in localized areas near its larval breeding sources, but is a vector of West Nile virus (WNV) and it has been implicated as a secondary vector of western equine encephalomyelitis (WEE) virus in the Central and Sacramento Valleys. This species is most commonly found in intermittently flooded areas such as duck clubs and wildlife refuges. Aedes melanimon are very aggressive mosquitoes that readily feed on mammals and humans and can emerge as soon as five days after eggs hatch.

Common Name: Western Treehole Mosquito
Scientific Name:
Aedes sierrensis

Aedes sierrensis is a major nuisance mosquito usually associated with the foothill regions in Butte County. This mosquito is the primary vector of Dog Heartworm. Larvae are generally found in treeholes and containers that have a lot of leafy material. Eggs hatch with the initial fall rains and over winter as larvae. This species of mosquito is a very small aggressive mosquito that usually surfaces in early spring and will be active into the summer months. Aedes sierrensis is a vicious biter of humans and other large mammals.

Common Name: Western Malaria Mosquito
Scientific Name:
Anopheles freeborni

Anopheles freeborni is one of Butte County's most abundant pests and is the primary vector of Malaria. Larvae prefer clear, fresh water in sunlit or partially shaded pools. This mosquito is most commonly found in rice fields and roadside ditches with grass. An aggressive mosquito, most Anopheles freeborni commonly feed on mammals or humans and are most active at dawn and dusk.

How You Can Minimize Adult Mosquitoes

  • Properly maintain swimming pools
  • Empty and invert any container that holds water
  • Change water frequently in bird baths and fountains
  • Stock ornamental ponds with mosquitofish
    (call BCMVCD to schedule a pick-up/delivery)
  • Check and clean rain gutters and downspouts
  • Avoid over irrigation of lawns and fields

Personal Protection from Mosquitoes

  • Reduce outdoor activity around dawn and dusk
  • Wear long pants and shirts with long sleeves
  • Use approved insect repellent
  • Seal all openings on your window screens and doors to prevent mosquitoes from entering your home.
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