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Mosquitoes

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Services -> Mosquitoes

Requesting Service for Mosquito Problems

If you would like your home inspected for mosquitoes, you can call our district office at (650) 344-8592. Please provide the following:

  • Name, Address, Cross Street, and Day Time phone number
  • Time of day you are bitten (morning, afternoon, evening)
  • Where you are bitten, inside or outside
  • Sample of the mosquito in a small container (dead or alive, but intact)
You do not need to be home in order to have your property surveyed or treated for mosquitoes. If there is street access to your yard, please indicate this, as well as any obstacles (locked gates, dogs, etc.).

Mosquitoes of San Mateo County:


Common Mosquitoes:

Mosquitoes: Characteristics:
Culex pipiens/quinquefasciatus
"The Northern House Mosquito"
Culex pipiens / quinquefasciatus are two species that are very similar and are separated only by geographic barriers.
  • Body: Brown, medium-sized mosquito
  • Legs: Brown and unbanded
  • Season: Year-round, peaking during summer and fall
  • Larval Habitat: In warm, sheltered foul or polluted water, such as fish ponds, catch basins, waste treatment ponds, neglected swimming pools.
  • Biting Behavior: Feeds on birds and mammals. Readily enters homes and bites indoors at night.
  • Importance: Can transmit WNV, Western Equine Encephalitis, and St. Louis Encephalitis.
Culex tarsalis
"The Western Encephalitis Mosquito"
  • Body: Medium-size, brown with a white band on the proboscis, or biting part, and V's on the abdomen.
  • Legs: Black and white banded.
  • Season: Primarily Spring to Fall.
  • Larval Habitat: Wide range of habitats from clean to partially foul water; rain pools, irrigation water, ornamental ponds, and often agriculture.
  • Biting Behavior: Prefer birds, but often feed on humans at night.
  • Importance: Primary vector of West Nile virus, Western Equine Encephalitis, and St. Louis Encephalitis.
Culex erythrothorax
"The Tule Mosquito"
  • Body: Reddish-orange, medium-sized mosquito.
  • Legs: Brown and unbanaded
  • Season: Adults emerge from June through October.
  • Larval Habitat: Tules or cattails
  • Biting Behavior: Opportunistic, they feed on birds and people.
  • Importance: Can transmit Western Equine Encephalitis and St. Louis Encephalitis.
Culiseta incidens
"The Cool Weather Mosquito"
  • Body: Large, gray, black, and brown mosquitoes.
  • Legs: Black and white banded.
  • Season: Adults are present year-round
  • Larval Habitat: Clean, cool water with some shading such as, artificial depressions filled with rain, ground pools, and rock pools.
  • Biting Behavior: Actively feed on humans at dawn and dusk.
  • Importance: Can be a local pest.
Culiseta inornata
"The Large Winter Mosquito"
  • Body: Large, brown mosquito.
  • Legs: Brown and unbanded
  • Season: Adults are active fall to spring
  • Larval Habitat: Larvae are found in sunlit water with some shade.
  • Biting Behavior: Can feed on humans, but not frequently.
  • Importance: Not usually a major vector or pest.
Culiseta particeps
  • Body: Large, gray, black, and brown mosquito, similar to Cs. incidens.
  • Legs: Black and whit banded
  • Season: Year-round
  • Larval Habitat: Banks of natural water and shaded clear ponds containing algae and debris.
  • Biting Behavior: Prefer large animals but will feed on humans in shaded areas.
  • Importance: Not usually a major pest or vector.
Aedes sierrensis
"Western Treehole Mosquito"
  • Body: Black with contrasting white scales
  • Legs: Black with white stripes
  • Season: Adults are active in spring, but can be found in summer and fall
  • Larval Habitat: Treeholes or small containers
  • Biting Behavior: Vicious all day and night. Prefer shaded areas.
  • Importance: Major pest and vector of Dog Heartworm

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Seasonal Mosquitoes:

Mosquitoes: Characteristics
Aedes squamiger
"The California Salt Marsh Mosquito"
  • Body: Dark and medium sized
  • Legs: Nothing notable
  • Season: Adults emerge in March and remain active through June
  • Larval Habitat: Coastal salt marsh
  • Biting Behavior: Vicious day biters, they can fly up to 20 miles to take a blood-meal, and return to the marsh to lay eggs.
  • Importance: Major Pest when it breeds
Aedes dorsalis
"The Summer Salt Marsh Mosquito"
  • Body: Whitish to yellow
  • Legs: Brown
  • Season: Adults are active late spring into the fall
  • Larval Habitat: Tidal or reclaimed marshes, or inland irrigated pastures
  • Biting Behavior: Vicious all-day biters, they can fly far for a blood meal, return to the marsh to lay eggs
  • Importance: Major pest and secondary vector for Western Equine Encephalitis
Aedes washinoi
"The Fresh Water Mosquito"
  • Body: Black with white scales
  • Legs: Black with white scales
  • Season: Adults emerge late winter to early spring
  • Larval Habitat: Freshwater ground pools, shaded pits near rivers or streams
  • Biting Behavior: Active day biters, but do not move more than a 1/2 mile from a larval source
  • Importance: A localized pest in some areas

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Less Common Mosquitoes:

Mosquitoes: Characteristics
Anopheles hermsi
"Southern California Malaria Mosquito"
  • Body: Slender, medium-sized brown mosquito
  • Legs: Brown and unbanded
  • Season: Adult activity peaks in June and July
  • Larval Habitat: Matted cattails and roots of willows, river margins, streams, and pools
  • Biting Behavior: Aggressive biters at sunrise and sunset
  • Importance: Malaria vector
Anopheles punctipennis
"The woodland malaria mosquito"
  • Body: Medium-sized brown body with a long gray stripe along the abdomen.
  • Legs: Brown and unbanded.
  • Season: Adults are active in spring and summer.
  • Larval Habitat: Grassy pools along creeks and permanent rivers.
  • Biting Behavior: Mostly feed on animals other than humans.
  • Importance: Local vector of malaria in streams and foothills.
Anopheles franciscanus
  • Body: Brown and medium sized
  • Legs: Nothing notable
  • Season: Active in spring and summer
  • Larval Habitat: Larvae are found in shallow, sunlit pools at the edge of streams
  • Biting Behavior: Rarely bites humans
  • Importance: Rarely a malaria vector
Anopheles occidentalis
  • Body: Slender, medium-sized brown body.
  • Legs: Brown and unbanded
  • Season: Active in spring and summer
  • Larval Habitat: Larvae live in small pools and moving streams, ponds, and lakes.
  • Biting Behavior: Do not prefer to feed on humans.
  • Importance: Inefficient malaria vector
Culex stigmatosoma
"The Banded Foul Water Mosquito"
  • Body: Medium-sized brown mosquito with ovals on the abdomen.
  • Legs: Black and white banded.
  • Season: Adult activity peaks in the summer months.
  • Larval Habitat: Natural and man made polluted waters such as sewage and dairy ponds.
  • Biting Behavior: Feed primarily on birds and rarely bite humans.
  • Importance: Secondary amplification of St. Louis Encephalitis.
Coquillettidia perturbans
  • Body: Medium sized brown mosquitoes with white at the tips of their palpi.
  • Legs: Brown and banded.
  • Season: Adults are active in June and July.
  • Larval Habitat: Permanent freshwater with cattails and tules. Larvae breathe by poking their siphons in the stems of water plants.
  • Biting Behavior: Feeds on large mammals, including humans, after sunset.
  • Importance: Vectors of encephalitis viruses.
Orthopodomyia signifera
Picture coming soon
  • Body: Thorax has distinct, narrow lines of white scales on it.
  • Legs: Broad white rings on tarsi.
  • Season: Adult activity peaks August - September
  • Larval Habitat: They live in hollowed out tree cavities and man-made containers
  • Biting Behavior: Prefer to feed on birds.
  • Importance: Not considered a vector or a pest due to its limited distribution in San Mateo County.

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