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How to identify it
- Small, delicate, two-winged flies; females have a long, slender proboscis for piercing skin, and the long, slender wings are covered with small scales. Missouri's conservation department adds that the wing edges and veins carry a fringe of hairs and scales, the legs are long, and adults are about 1/4 to 1/2 inch long, not counting legs.[1][3]
- Only females feed on blood; males feed on plant juices and other sugars. Males can be told apart by their feathery antennae, according to Missouri.[1][3]
- Larvae ("wigglers") are black or brown and hang at the water surface to breathe; pupae ("tumblers") are comma shaped. Missouri notes that larvae breathe through tubes at the tip of the abdomen and wriggle downward when disturbed.[1][3]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Crane flies ("mosquito hawks") | Much larger, and despite the nickname they don't actually eat mosquitoes. Missouri groups crane flies and midges as the mosquito's look-alike cousins in the fly order.[1][3] |
| Non-biting midges | Look similar but lack the long, piercing proboscis and don't bite. Only female mosquitoes have the blood-feeding habit, and adult mosquitoes have scales on the wing veins.[1][3] |
Where it lives
Larvae develop in stagnant or still water: pools, tree holes, tires, flowerpot saucers, rain barrels, clogged gutters and anything that holds water. Invasive Aedes mosquitoes can breed in water as small as a bottle cap.[1]
Biology and life cycle
In summer the whole life cycle, egg to adult, can take a week or less. Development times vary by source: CDC says Culex and Aedes eggs take 7 to 10 days to become adults, Illinois Extension says larvae take 5 to 7 days, and Missouri says larvae spend about a week in the water and pupae 2 to 3 days.[1][4][5][2][3]
Some species lay egg rafts of 100 or more on water; others, including Aedes, lay eggs on damp surfaces that hatch when flooded, even months later. CDC says a Culex raft holds 100 to 300 eggs and Missouri puts a female's batch at 100 to 400 or more. Sources differ on how long dry eggs last: CDC says Aedes eggs can survive drying for up to 8 months, UC says flooding may come months or even years later, and Illinois says floodwater mosquito eggs can wait more than two years.[1][4][3][5][2]
Some adults can fly several miles from where they developed. Others stay close to home: CDC says Culex mosquitoes don't fly long distances but have been known to go up to 2 miles, and Illinois says the northern house mosquito and Asian tiger mosquito seldom travel more than half a mile.[1][4][2]
Adult Culex mosquitoes are most active from dusk to dawn and rest in grass, shrubs and other cool, damp vegetation during the day, while CDC says Aedes mosquitoes can bite during the day and night.[4][9]
Mosquitoes that get indoors rest in dark, humid places such as under sinks, in showers and closets, and under furniture, and CDC says they can start laying eggs indoors.[6]
Damage and signs
- Most bites are harmless. MedlinePlus says the usual reaction is an itchy bump, an immune response to mosquito saliva, that goes away in a day or two; some people get blisters or large hives, and in rare cases a severe allergic reaction (anaphylaxis), which is a medical emergency.[11]
Health risk
Culex mosquitoes spread West Nile, St. Louis encephalitis and eastern equine encephalitis viruses in U.S. states. CDC estimates that 80% of West Nile infections cause no symptoms and that less than 1% of infected people develop neuroinvasive disease such as meningitis or encephalitis. Aedes aegypti and Aedes albopictus spread dengue, Zika and chikungunya viruses. Mosquitoes also spread the roundworm that causes heartworm disease in dogs.[4][8][9][10]
Control
Prevention
Drain or eliminate anything that holds water for more than a few days: change bird bath water weekly, store containers upside down, clean gutters, and screen or seal rain barrels. CDC says to do this once a week: empty and scrub, turn over, cover or throw out tires, buckets, toys, pools, birdbaths, flowerpot saucers and trash containers. It also suggests filling tree holes and repairing cracks in septic tanks.[1][6][7]
Wear loose-fitting long sleeves and pants and use an EPA-registered repellent. CDC lists DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) and 2-undecanone, and says not to use OLE or PMD on children under 3. Permethrin goes on clothing and gear, never directly on skin.[7][1][11]
Keep them out
Keep fine-mesh window and door screens in good repair. CDC adds keeping doors, including garage doors, closed and using air conditioning when possible.[1][6][7]
Biological control
Treat water you can't drain with Bti (Bacillus thuringiensis israelensis) products such as dunks, which kill larvae and last about 30 days; mosquitofish from your vector control district can stock isolated ponds and neglected pools. Illinois says Bti donuts, briquettes and granules can control larvae for a month or more and suggests stocking garden ponds with minnows or other surface-feeding fish; koi won't help.[1][2]
Pesticides
Outdoor sprays and foggers give only temporary reduction of adults; bug zappers are counterproductive because they mostly kill insects that prey on mosquitoes. CDC says an indoor spray or fogger kills mosquitoes quickly and may need to be reapplied, but insecticide alone will not keep a home free of them.[1][6]
When to call a professional
Contact your local mosquito and vector control district about problem sources such as neglected pools or storm drains.[1][4]
Where sources disagree
Egg survival: CDC says dry Aedes eggs survive up to 8 months; UC says flooding can hatch eggs months or even years later; Illinois says floodwater mosquito eggs can wait more than two years.[5][1][2]
Flight range: UC says some adults fly several miles; CDC says Culex can go up to 2 miles; Illinois says the northern house and Asian tiger mosquitoes seldom go beyond half a mile, which is why clearing water around your own neighborhood helps.[1][4][2]
Common questions
- Do bug zappers control mosquitoes?
- No. Many of the insects they kill are mosquito predators.[1]
- What's the most effective thing I can do?
- Eliminate standing water that holds larvae, and use screens and repellent for protection.[1][6][7]
- Do mosquitoes bite during the day?
- Some do. CDC says mosquitoes bite day and night: Culex adults are most active from dusk to dawn, while Aedes mosquitoes can bite during the day as well as at night.[7][4][9]
- How often should I dump standing water?
- Once a week. CDC says to empty, scrub, turn over, cover or throw out anything that holds water weekly, and Illinois notes that larvae can develop in as little as one cup of water.[6][2]
Sources
- University of California Statewide IPM Program, “Pest Notes: Mosquitoes, Publication 7451 (revised April 2020).” ipm.ucanr.edu/legacy_assets/PDF/PESTNOTES/pnmosquitoes.pdf (accessed 2026-11-11)
- University of Illinois Extension, “Mosquitos.” extension.illinois.edu/insects/mosquitos (accessed 2026-11-11)
- Missouri Department of Conservation, “Mosquitoes (Field Guide).” mdc.mo.gov/discover-nature/field-guide/mosquitoes (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “About Culex Mosquitoes.” www.cdc.gov/mosquitoes/about/life-cycle-of-culex-mosquitoes.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Life Cycle of Aedes Mosquitoes.” www.cdc.gov/mosquitoes/about/life-cycle-of-aedes-mosquitoes.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Mosquito Control at Home.” www.cdc.gov/mosquitoes/mosquito-control/mosquito-control-at-home.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Preventing Mosquito Bites.” www.cdc.gov/mosquitoes/prevention/index.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “Clinical Signs and Symptoms of West Nile Virus Disease.” www.cdc.gov/west-nile-virus/hcp/clinical-signs/index.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “How Dengue Spreads.” www.cdc.gov/dengue/transmission/index.html (accessed 2026-11-11)
- Centers for Disease Control and Prevention, “About Dirofilariasis.” www.cdc.gov/dirofilariasis/about/index.html (accessed 2026-11-11)
- MedlinePlus, U.S. National Library of Medicine, “Mosquito Bites (Health Topic).” medlineplus.gov/mosquitobites.html (accessed 2026-11-11)
- iNaturalist, “Culex pipiens taxon page (order and family).” www.inaturalist.org/taxa/1096295 (accessed 2026-11-11)