The short version
Around San Francisco, mosquito season runs from about March into November. Start by dumping standing water every week. A barrier spray every few weeks adds steady relief.
- Dump standing water every week.
- Daytime biters are usually tiger mosquitoes.
- Barrier sprays last about three to four weeks.
- Larvicide handles water you can’t drain.
- Use repellent with DEET, picaridin or IR3535.
Anyone in San Francisco tired of mosquito bites at home.
What to look for
Mosquitoes breed in standing water, even a bottle cap's worth. In summer heat, eggs become biting adults in about a week. Often the source is a neighbor's yard or a storm drain.
- 1Ornamental pond with no fish or pump.
- 2Wriggling larvae in birdbaths, buckets, or saucers.
- 3Tarps, toys, or tires holding rainwater.
- 4Kiddie pools left full for days.
- 5A sump pit or crawl space holding water.
- 6Mosquitoes indoors resting on walls or in closets.
Why it’s worth acting soon
- Each new generation is bigger than the last.
- Bites can spread West Nile virus.
- Itchy welts, especially for kids.
- Heartworm risk for dogs.
bite, to get protein for their eggsOnly female mosquitoesUS CDC in standing water, from a bottle cap to a pondMosquitoes breedUS EPA West Nile virus is the most common mosquito-borne disease in the U.S.Mosquito diseasesUS CDC Treatment options and typical costs
Property Inspection for Breeding Sites
$0–$150 (often bundled with a first treatment)
Before anything is sprayed, a pro in San Francisco should work out which mosquito you have and where the larvae are growing. Container breeders and floodwater breeders call for different tactics.
- Time
- 30–60 minutes
- Best for
- Every yard; finds where mosquitoes actually breed
Monitoring and Seasonal Plans
$50–$150 per follow-up visit; $350–$900 per season bundled
Ask your pro what happens if bites come back between visits. Many plans include a re-spray within a set window. Ask first.
- Time
- 15–30 minutes per check; season runs spring through first frost
- Best for
- Anyone who wants the yard usable all summer
Barrier (Residual) Yard Treatment
$75–$200 per visit; $350–$900 per season
A barrier treatment coats the undersides of leaves, shrubs, and shaded surfaces where adult mosquitoes rest during the day around your San Francisco home. Adults that land there pick up a lethal dose.
- Time
- 20–45 minutes per visit, repeated every 3–4 weeks
- Best for
- Shaded yards with shrubs, ivy, and dense landscaping
Misting Systems and In2Care-Style Stations
misting $2,000–$4,500 installed plus refills; stations $200–$500 per season
Misting systems put product into the air on a schedule whether mosquitoes are present or not, which raises resistance and pollinator concerns in San Francisco neighborhoods. Ask about sensors, timers, and off-switch etiquette.
- Time
- Misting: half a day. Stations: under an hour.
- Best for
- Specific yards: heavy outdoor use or spray-averse owners
Prices are typical published ranges. Ask what’s included before you compare quotes.
Leaf-clogged gutters and downspouts hold water out of sight. Clearing them in fall means fewer places to breed in spring.Which mosquitoes bite around San Francisco.
Asian tiger mosquitoes are common around San Francisco. They're black-and-white and bite by day. They breed in small containers. House mosquitoes (Culex) bite from dusk into the night. They breed in storm drains. They're the main West Nile carriers. Near the coast, salt-marsh mosquitoes can fly into San Francisco from miles away.
Local mosquitoes conditions in San Francisco.
San Francisco sits in a mediterranean climate, and that sets the pace for mosquito activity here: late spring through early fall; year-round in the deep south. In San Francisco, the area is mostly urban, so mosquitoes pressure can differ from one block to the next depending on how tight the entry points are and how much food, water, or shelter is close by. An inspection in San Francisco usually starts outside and works inward, checking the foundation, gaps around doors and windows, and any moisture or clutter near the structure first. Knowing San Francisco's seasonal timing lets you schedule treatment before the busy stretch rather than after it, which usually means faster service and a more accurate quote. A provider who works San Francisco and California every day can point out the specific conditions that matter most here, and getting the scope, price, and follow-up terms in writing makes it easier to compare options.
Mosquitoes that bite indoors usually slip in through gaps around doors or torn window screens.Mosquito season in San Francisco.
West Nile cases usually peak in late summer. Plan on regular visits. That's a long season.
A year of mosquitoes in San Francisco.
- Winter: a good time to fix drainage and low spots. - Fall: numbers stay high. Keep gutters clear of leaves. - Summer: with highs near 67°F in San Francisco, check water twice a week. - Spring: the first wave arrives early in San Francisco. Start treatments then.
The weekly water walk.
- Gutters: clear leaves so water drains. - Saucers and pots: empty them or add sand. - Toys and buckets: store them upside down. - Tarps and covers: pull them tight so water runs off. - Birdbaths: change the water twice a week. - Pet bowls: refresh daily. - AC drip lines and downspouts: make sure water drains away. - Tree holes: fill them with sand.
Avoiding bites.
- Repellent: DEET, picaridin, IR3535 or oil of lemon eucalyptus. - Clothing: long sleeves and pants help at dusk. - Fans: a patio fan keeps weak-flying mosquitoes away. - Screens: repair holes in window and door screens. - Timing: tiger mosquitoes bite by day; house mosquitoes at dusk.
Low-cost ways to cut mosquitoes.
- Mosquito dunks: Bti tablets kill larvae in rain barrels and ponds. - Mosquito fish: they eat larvae in ornamental ponds. - Pumps and fountains: moving water breeds far fewer mosquitoes. - Trimming: thin out dense shrubs and tall grass. - Lights: yellow bug lights attract fewer insects to the porch.
Mosquito or look-alike?
- Crane flies: look like giant mosquitoes. They don’t bite. - Non-biting midges: swarm near water at dusk. Harmless, just annoying. - No-see-ums: tiny biting gnats near marshes. Screens need a finer mesh. - Mosquitoes: slim, long legs, and a needle-like mouth.
When a bite needs a doctor.
Spreading swelling or an infected-looking bite needs a check too. See a doctor for high fever, stiff neck or confusion. About one in five get a fever, headache or body aches. Most people infected with West Nile virus never feel sick. Most bites just itch for a few days.
Protecting your pets.
Keep pets inside while a yard spray dries. Change pet water bowls daily. Ask your vet about year-round heartworm prevention. Cats can too. Dogs get heartworm from mosquito bites.
What a treatment visit looks like.
Most plans repeat every three to four weeks. Then they spray shady shrubs, where adults rest. Larvicide goes in water you can't drain. They dump or treat standing water. The tech walks the yard first. A visit usually takes 20 to 45 minutes.
Rain barrels and ponds.
- Barrels: cover openings with fine mesh. - Ponds: fish and moving water keep larvae down. - Bird baths: change the water every few days. - Gutters: clear them so water drains away. - Tarps: shake out any that hold rainwater. - Pool covers: drain standing water after rain.
Questions to ask before you sign.
- What product will you spray? - How often will you come? - Do you treat standing water too? - What happens if bites come back between visits? - How do you protect bees and flowers? - When can kids and pets go back outside?
What affects the price
- Gutter cleaning or drainage fixes bundled in.
- In2Care-style station count and servicing.
- Ponds, creeks, or wetland edges on the property.
- Misting system installation and refills.
- Special-event timing and rush scheduling.
- Commercial or multi-unit property.
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What's your biggest mosquito frustration?
When to call for help
Ponds, drains and dense shrubs are hard to handle yourself. early in the season, before the first big wave. Dumping water should come first. Call if bites still keep you indoors.
What you can do yourself
The biggest win is free: dump standing water every week. Use repellent and run a fan on the patio. A pro adds larvicide for water you can't drain. They also spray where adults rest, every few weeks.
Mosquitoes in San Francisco
In denser parts of San Francisco, storm drains, catch basins and gutters are big breeding spots. Summer highs around 67°F in San Francisco speed up the life cycle, and average humidity near 75% keeps adults active. With about 24 inches of rain a year in San Francisco, any container left out will hold water within days.
Local research
Mosquitoes in San Francisco, CA: what the public record shows
Before you compare quotes, it helps to know which mosquitoes actually live in California, when they are busiest around San Francisco, and what the state figures look like. Everything below links to the agency or university page it came from.
West Nile neuroinvasive disease cases, 2024
Neuroinvasive counts are the most reliable state comparison because nearly all severe cases are diagnosed and reported.
CDCMosquito species recorded in California
- Yellow fever mosquito (Aedes aegypti) — CDC lists Aedes aegypti as more likely than Ae. albopictus to spread dengue, Zika, and chikungunya; prefers human hosts and lives in and around homes. Tropical, subtropical, and…
When mosquitoes are busiest around San Francisco
Washington DOH: detections from May (earliest) to October (latest). California reports its heaviest WNV activity in late summer; CDC peak is late August to early September.
CDC lists California among states with limited local dengue spread from Aedes aegypti.
Rules that apply in California
For context, nationally
- 1,808 — West Nile virus disease cases reported, 2024. CDC
- 1,347 (75% of cases); 173 deaths — West Nile neuroinvasive disease cases, 2024. CDC
Sources: CDC; California Department of Public Health / MVCAC; Potential Range of Aedes Mosquitoes. Figures are quoted as the source prints them. How we check our sources
Simple ways to keep mosquitoes away
- Repair torn window and door screens.
- Trim shrubs and ivy to reduce resting cover.
- Rake leaf litter from shaded beds.
- Keep pools chlorinated and covered when unused.
- Talk with neighbors about shared breeding sites.
- Book barrier treatments before the season starts.
When you compare quotes, look at the season total, how many visits it covers and what happens if the bites come back.Did you know?
Tiger mosquitoes arrived in used tires in the 1980s
Over 3,500 mosquito species exist worldwide
Questions people ask
Can I get rid of mosquitoes permanently?
Removing water and spraying resting spots cuts them down a lot. They fly in from nearby. Not completely.
What is the difference between larvicide and barrier spray?
Most plans use both. Barrier spray goes on leaves where adults rest. It stops larvae from maturing.
What does a mosquito inspection involve?
Gutters, saucers, tarps and low spots get checked first. They also check shady spots where adults rest. The tech walks the yard looking for standing water.
Can mosquito control help with West Nile risk?
It can lower it by cutting the number of biting mosquitoes. Repellent and dumping standing water still matter most.
What are In2Care stations and do they work?
They work best against container breeders like tiger mosquitoes. Mosquitoes visit, then carry larvicide to other water. They're small water traps.
What do most homeowners do about yard mosquitoes?
In San Francisco, mosquito control works by removing standing water, treating the water that cannot be drained, and applying barrier treatments where adults rest. In San Francisco, because they keep breeding through the season, an ongoing plan usually works best.
When is mosquito season in San Francisco?
It runs from about March into November. Daytime biters are tiger mosquitoes; evening biters are usually house mosquitoes.
Do mosquitoes in San Francisco carry West Nile?
Repellent and dumping standing water are your best protection. Cases usually peak in late summer. West Nile is found in every lower-48 state, California included. They can.
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Sources (11)
The facts in this article come from the public sources listed above. Every home is different, so ask the company you talk to about pricing and what’s included. Published by Mosquito Exterminator · Updated September 11, 2026 · How we write these guides