The essentials in 30 seconds
Mosquitoes need standing water to breed. Females lay eggs on or just above the water, the larvae ("wigglers") hang at the surface to breathe, and in summer the whole cycle from egg to biting adult can take a week or less. That is why CDC's advice is a weekly routine: empty, scrub, turn over, cover or throw out anything that holds water, inside and outside. Water you cannot empty, such as an ornamental pond or a rain barrel, can be treated with a Bti larvicide, which EPA says affects only the larvae of mosquitoes, black flies and fungus gnats. Yard sprays give temporary relief and can harm bees and butterflies. For your own protection, use screens, air conditioning when you can, a fan on the patio and an EPA-registered repellent.
- Even a bottle cap of water can hold larvae.
- Bug zappers, ultrasonic devices and repellent wristbands are poor buys, according to University of California entomologists.
- If the mosquito biting you by day is black with white stripes, read our Asian tiger mosquito guide.
What mosquito larvae look like and where to find them
Look into any container of rainwater that has stood for a few days in summer. Mosquito larvae are easy to spot once you know the signs.
| Stage | What you see | Notes |
|---|---|---|
| Eggs | Some species lay floating rafts of 100 or more; others lay single eggs on damp walls just above the water line | Container-breeding Aedes eggs survive drying for months and hatch when water returns |
| Larva ("wiggler") | Thin, usually black or brown, hanging head-down from the surface; it wriggles down when the water is disturbed | The first stage is almost too small to see; larvae molt three times and grow each time |
| Pupa ("tumbler") | Small, dark and comma-shaped, rolling and tumbling when disturbed | Pupae do not feed, so larvicides that must be eaten, such as Bti, do not affect them |
| Adult | Emerges from the pupa in 1 to 2 days | Only females bite; some species fly several miles from where they hatched |
A quick test: tap the side of the bucket. If small dark specks dive and then wriggle back up to the surface, you have mosquito larvae. Empty the water onto dry ground or a lawn, where they cannot survive, and scrub the inside of the container.
Where they breed around the house
| Where | Why it breeds mosquitoes | What to do |
|---|---|---|
| Plant saucers, buckets, toys, wheelbarrows | Rainwater sits for days | Empty and scrub weekly, store upside down or under cover |
| Birdbaths and pet water bowls | Still water in the open | Change the water and scrub at least weekly |
| Clogged gutters and downspouts | Leaves dam the water | Clear them; see our gutter cleaning guide |
| Tarps, grill covers, pool covers | Water pools in folds | Pull tight or drain after rain |
| Old tires and tree holes | Dark, sheltered water | Store tires under cover or recycle them; fill tree holes |
| Rain barrels and water butts | Large open surface | Fit a tight lid or mesh with holes smaller than a mosquito |
| Kiddie pools and neglected pools | Standing water for weeks | Drain and turn kiddie pools over; keep pools treated and circulating; see pool cleaning |
| Septic tank vents and cracks | Dark, damp spaces | Repair cracks and screen open vent pipes |
| Ornamental ponds | Still edges with plants | Add a fountain or pump to keep water moving, or use a larvicide |
| Indoors: vases, saucers, plant water | Forgotten still water | Change and scrub weekly |
The weekly water check, step by step
Because the cycle can be as short as a week in hot weather, a weekly check stops larvae before they become adults. Do it from spring until the first hard frosts.
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01
Pick a fixed day
Tie it to something you already do weekly, like taking out the trash, so it becomes a habit.
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02
Walk the whole lot
Front yard, back yard, side passages, under decks, the patio and any balcony. Look for anything that holds a spoonful of water.
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03
Empty it
Tip out saucers, buckets, toys, covers and birdbaths onto dry ground.
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04
Scrub the inside
Some species glue their eggs to the walls above the water line. A stiff brush removes them.
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05
Turn over, cover or throw out
Store containers upside down or under a roof and get rid of what you do not need.
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06
Check gutters and drains
Clear leaves and mud so water runs off.
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07
Treat what you must keep
Use a larvicide labeled for mosquitoes in water you cannot empty, as described below.
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08
Talk to the neighbors
Mosquitoes do not stop at the fence. A street that does the routine together sees bigger results.
Larvicides: Bti dunks and other options
Larvicides kill mosquitoes before they can fly and bite. Extension entomologists consider them the longest-lasting, most consistent form of chemical control, because they act where mosquitoes are concentrated. CDC advises using them on water that cannot be emptied or covered and is not used for drinking, always following the label.
| Active ingredient | How it works | Notes |
|---|---|---|
| Bti (Bacillus thuringiensis israelensis) | A soil bacterium; its toxins kill larvae that eat it | EPA finds no risk to people and minimal toxicity to honey bees; sold as dunks and granules; dunks last about 30 days |
| Methoprene | An insect growth regulator that stops larvae becoming adults | Follow the label for where it may be used |
| Spinosad | A naturally derived insecticide for standing water | Follow the label for where it may be used |
How to use Bti well:
- Read the label for the dose per area of water and how often to replace it.
- Check whether the product is allowed in the water you have in mind. EPA notes that some Bti products may be used in certain drinking-water containers such as cisterns and others may not.
- Remember that Bti has no effect on pupae, so a few adults can still emerge in the first days after treatment.
- Treat birdbaths only if you cannot change the water weekly; changing it is simpler.
Yard sprays and barrier treatments: what they can and cannot do
Barrier or perimeter treatments are insecticides, usually pyrethroids, sprayed onto shrubs, foliage and structures where adult mosquitoes rest. University of Wisconsin Extension notes that they reduce adult activity only temporarily, because they do nothing about the water where larvae develop, and mosquitoes return or fly in from outside the yard. The University of California calls sprays and foggers a short-term measure, useful before a party but with no lasting effect.
The residues are designed to stay on leaves for days to weeks. Wisconsin Extension cites studies in which monarchs and honey bees were harmed several weeks after a barrier treatment, and it flags regular, all-season spraying schedules as a concern for beneficial insects.
If you still want a professional treatment, ask the company:
- Are you certified to apply pesticides in this state?
- Will you inspect for standing water first and use integrated pest management, or only spray?
- What is the active ingredient, how long does it last and what happens if it rains?
- What is the re-entry interval for people and pets?
- Can I see the product label and safety data sheet before you start?
- How will you protect pollinators, flowering plants and nearby water?
CDC adds that if you spray adults yourself, aim at the dark, humid places where they rest, such as under patio furniture, in a carport or garage, and follow the label exactly.
Repellents that work on people
CDC and EPA recommend repellents registered by the US Environmental Protection Agency. Look for an EPA registration number on the label and one of these active ingredients: DEET, picaridin (icaridin outside the US), IR3535, oil of lemon eucalyptus (OLE), para-menthane-diol (PMD) or 2-undecanone.
| Question | What to know |
|---|---|
| How long will it last? | UC entomologists note most products protect for 4 hours or less; under 10 % active ingredient may give only 1 to 2 hours, and above about 50 % adds little |
| Children? | Skip OLE and PMD under age 3; put repellent on your hands first, then on the child's face; keep it off their hands, eyes, mouth and cuts |
| Sunscreen? | Sunscreen first, repellent on top |
| Clothing? | Long, loose sleeves and pants; permethrin-treated clothing and gear, never permethrin on skin |
| Natural products? | CDC says the effectiveness of unregistered repellents, including some natural ones, is unknown |
For a full comparison of active ingredients, see our Asian tiger mosquito guide.
Keep them out of the house and off the patio
- Screens: fit fine mesh on windows and doors and patch any holes. Keep doors closed, including the garage door.
- Air conditioning: CDC recommends it where available, with windows shut.
- Indoor resting spots: mosquitoes hide under sinks, in showers, closets, laundry rooms and under furniture. Check indoor vases and saucers weekly too.
- A fan on the patio: mosquitoes are weak fliers. Cornell University notes they manage about 1.5 miles per hour, while a typical house fan blows far harder, and research in the Journal of Medical Entomology found wind and DEET the two most effective ways to avoid them. Point a box or pedestal fan across where you sit.
- Netting: cover strollers and baby carriers with mosquito netting.
What does not work well
| Product | What the evidence says |
|---|---|
| Bug zappers (electric grids) | UC IPM calls them counterproductive: they kill many insects, including ones that eat mosquitoes |
| Ultrasonic and electronic repellers | Listed as ineffective by UC IPM |
| Repellent wristbands | Listed as ineffective by UC IPM |
| "Mosquito plant" (citronella-scented geranium) | Listed as ineffective by UC IPM |
| Vitamin B1, garlic and brewer's yeast | Listed as ineffective by UC IPM |
| Citronella candles and coils | Work best with little air movement; outdoors only |
| CO2 mosquito traps | Catch only a small share of the mosquitoes they attract; several are needed per yard |
Mosquitoes and disease
Most bites cause only an itchy bump, but some mosquitoes carry viruses. In the US, West Nile virus is the most widespread: University of California figures show about 80 % of infected people have no symptoms, about 20 % get a mild illness, and about 1 in 150 develop a serious illness of the nervous system. There is no human vaccine. Other viruses spread by mosquitoes in parts of the world include dengue, Zika, chikungunya and yellow fever, and mosquitoes also pass heartworm to dogs.
Your local health department or mosquito control district tracks which viruses are active near you. If you feel ill with a fever during mosquito season or after travel, see a doctor and mention the bites or the trip.
When to call for help
- Your weekly routine has run for three or four weeks and bites remain heavy: the source may be a neighbor's pool, a storm drain or a roof gutter you cannot reach.
- There is a large pond, abandoned pool or flooded area you cannot empty.
- You want a treatment near flowers, vegetables or water and need advice that protects pollinators.
Many counties and cities run a mosquito control program: report breeding sites, neglected pools and biting problems to them first. If you hire a pest control company, ask for an inspection for breeding water before any spraying.
Mosquitoes: frequently asked questions
How do I get rid of mosquitoes in my yard?
Remove standing water every week, treat water you must keep with a Bti larvicide, and protect yourself with screens, a fan and an EPA-registered repellent.
What do mosquito larvae look like?
Thin black or brown "wigglers" hanging from the water surface. They dive when disturbed and wriggle back up to breathe.
How long does it take mosquito larvae to become adults?
In summer, a week or less from egg to adult, depending on water temperature.
Are Bti mosquito dunks safe?
EPA finds that Bti poses no risk to people and has minimal toxicity to honey bees. Follow the label, especially for drinking-water containers.
Do mosquito yard sprays work?
They reduce adult mosquitoes for a short time but leave the breeding water untouched, and they can harm bees and butterflies.
Do bug zappers kill mosquitoes?
University of California entomologists say they are counterproductive, killing mainly other insects, including mosquito predators.
What is the best mosquito repellent?
One registered by EPA with DEET, picaridin, IR3535, oil of lemon eucalyptus, PMD or 2-undecanone, used as the label says.
Why are there so many mosquitoes in my house?
Usually an open door, a torn screen or indoor water such as vases and plant saucers. Fix the screens and empty indoor water weekly.
Sources
Official health and university guidance, checked on 27 October 2026.
- CDC · Mosquito control at home ↗Weekly empty, scrub, turn over, cover or throw out routine; mesh, septic tanks, larvicides only on non-drinking water; resting spots for adult sprays; screens and indoor checks.
- CDC · Preventing mosquito bites ↗EPA-registered active ingredients, children and age limits, sunscreen order, permethrin, screens, air conditioning and unregistered repellents.
- US EPA · Bti for mosquito control ↗What Bti is, which larvae it affects, home containers, safety for people and honey bees, and checking the label for drinking water.
- University of California IPM · Mosquitoes ↗Larvae and pupae, life-cycle timing, breeding sites, larvicides, limits of sprays, repellent duration, ineffective gadgets, mosquitofish and West Nile virus figures.
- University of Wisconsin–Madison Extension · Tips for mosquito control treatments ↗Larvicides versus barrier sprays, pyrethroid residues, harm to monarchs and honey bees, moving pond water and questions to ask an applicator.
- Cornell University · A new method to avoid mosquitoes ↗Mosquito flight speed, fan wind speed and the study on wind and DEET.
Bitten on the deck tonight?
Walk the yard with a brush this weekend, empty every container that holds water and set a reminder to repeat it every seven days.