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Northern House Mosquito

Culex pipiens

Size47 mm
Colony Size1001,000
Active Season:Crepuscular (most active at dusk and dawn) and nocturnal—they create the high-pitched whine heard in bedrooms at night. Active May-September outdoors. Unlike many mosquito species that die off, Culex females can overwinter as adults in basements, sewers, crawl spaces, and other sheltered locations in Canada.

Common urban mosquito that breeds in stagnant water. Primary vector of West Nile virus in Canada.

Anatomy

Anatomical Details

Identification

ColourBrown with lighter bands on abdomen, pale banding on legs
Size47 mm

Distinguishing Features

  • Long proboscis for blood-feeding
  • Wings with scales along veins
  • Rests with body parallel to the surface (diagnostic posture)
  • Brownish/drab overall coloration (compared to boldly striped Asian Tiger Mosquito)
  • Pale bands on abdomen segments

Biology

Lifecycle

Unlike mosquito species that lay eggs singly, Culex lays eggs in a floating 'raft' of 100-300 eggs—resembling a speck of soot on the water surface. Egg rafts → larvae (wrigglers) → pupae (tumblers) → adults. Complete cycle in 10-14 days in warm weather.

Diet

Females require blood meals for egg production. Both sexes feed on nectar. Prefer birds but bite humans.

Nesting

Breed in strictly stagnant water rich in organic matter. A forgotten cup of water in the backyard is sufficient breeding habitat—they don't need a pond. Common sites: catch basins, bird baths, clogged eavestroughs, discarded tires, unused pools, and any water-holding container. Thrives in urban environments.

Signs of Infestation

Mosquitoes indoors at dusk

Adults entering through gaps to feed, especially in bedrooms.

Bites appearing overnight

Itchy welts on exposed skin after sleeping.

Wrigglers in standing water

Larvae visible in bird baths, buckets, or clogged gutters.

High-pitched whining

Wing beat frequency creates distinctive sound near ears.

Where They Nest

  • Catch basins and storm drains
  • Clogged roof gutters
  • Bird baths and ornamental ponds
  • Discarded tires and containers
  • Unused pools and hot tubs

Distribution in Canada

Abundant in urban areas across southern Canada. Primary nuisance and disease vector.

Regional Prevalence

High
Moderate
Low
Rare/Absent

Active Season

Crepuscular (most active at dusk and dawn) and nocturnal—they create the high-pitched whine heard in bedrooms at night. Active May-September outdoors. Unlike many mosquito species that die off, Culex females can overwinter as adults in basements, sewers, crawl spaces, and other sheltered locations in Canada.

Prevention

  • Eliminate standing water weekly (dump, drain, or cover)
  • Clean gutters regularly
  • Stock ornamental ponds with mosquitofish
  • Use screens on windows and doors
  • Apply larvicide to catch basins (municipal programs)

Professional Treatment

Barrier spray treatments on vegetation reduce adult resting sites. Larviciding in breeding areas. Most effective as part of integrated municipal program.

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Scientific Classification
Kingdom
Animalia
Phylum
Arthropoda
Class
Insecta
Order
Diptera
Family
Culicidae
Genus
Culex