The short version
Around San Mateo, mosquito season runs from about March into November. Treatment means removing water and treating what you can't drain. A barrier spray follows every few weeks.
- 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 Mateo tired of mosquito bites at home.
What to look for
In summer heat, eggs become biting adults in about a week. Often the source is a neighbor's yard or a storm drain. Mosquitoes breed in standing water, even a bottle cap's worth.
- 1A neighbor's pool turning green and untended.
- 2Bites getting worse after each wet spell.
- 3Adults resting under deck boards or in ivy.
- 4Ornamental pond with no fish or pump.
- 5Corrugated downspout extensions that never drain.
- 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 📅
Mosquito activity through the year in San Mateo
Spring
the first wave arrives early in San Mateo. Start treatments then.
Summer
with highs near 78°F in San Mateo, check water twice a week.
Fall
numbers stay high. Keep gutters clear of leaves.
Winter
a good time to fix drainage and low spots.
Treatment options and typical costs
Property Inspection for Breeding Sites
$0–$150 (often bundled with a first treatment)
Resting spots get a look as well: thick shrubs, ivy, the space under decks and shady fence lines around your San Mateo home. Knowing where adults hide shows where barrier spray matters.
- Time
- 30–60 minutes
- Best for
- Every yard; finds where mosquitoes actually breed
Source Reduction and Larviciding
$75–$150 per visit
Most breeding sites on a San Mateo lot can be cleared by hand, so this visit is also a chance to learn what to look for. A pro points them out so they stay gone.
- Time
- 45–90 minutes
- Best for
- Yards with standing water, clogged gutters, ponds, or drains
Misting Systems and In2Care-Style Stations
misting $2,000–$4,500 installed plus refills; stations $200–$500 per season
In2Care-style stations lure egg-laying females and dust them with larvicide. The females spread it to other water and die from a fungus they picked up, which is why San Mateo pros like them for container-heavy lots.
- Time
- Misting: half a day. Stations: under an hour.
- Best for
- Specific yards: heavy outdoor use or spray-averse owners
Barrier (Residual) Yard Treatment
$75–$200 per visit; $350–$900 per season
Relief usually shows within a day or two.
- Time
- 20–45 minutes per visit, repeated every 3–4 weeks
- Best for
- Shaded yards with shrubs, ivy, and dense landscaping
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.How mosquito treatment works in San Mateo.
First, find and remove the water where they breed. Then spray where the adults rest. Across San Mateo, the season runs from about March into November, so a plan usually starts in spring and runs to the end of the season. Larvicide handles water you can't drain, like ponds or drains. Barrier spray covers shady shrubs and leaves. Treatment has two parts.
Which mosquitoes bite around San Mateo.
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 Mateo from miles away. Asian tiger mosquitoes are common around San Mateo.
Mosquitoes that bite indoors usually slip in through gaps around doors or torn window screens.Mosquito season in San Mateo.
Plan on regular visits. West Nile cases usually peak in late summer. That's a long season.
A year of mosquitoes in San Mateo.
- Winter: a good time to fix drainage and low spots. - Spring: the first wave arrives early in San Mateo. Start treatments then. - Summer: with highs near 78°F in San Mateo, check water twice a week. - Fall: numbers stay high. Keep gutters clear of leaves.
The weekly water walk.
- Tree holes: fill them with sand. - 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.
Avoiding bites.
- Timing: tiger mosquitoes bite by day; house mosquitoes at dusk. - 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.
Low-cost ways to cut mosquitoes.
- Lights: yellow bug lights attract fewer insects to the porch. - 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.
Mosquito or look-alike?
- Mosquitoes: slim, long legs, and a needle-like mouth. - 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.
When a bite needs a doctor.
Most people infected with West Nile virus never feel sick. About one in five get a fever, headache or body aches. See a doctor for high fever, stiff neck or confusion. Spreading swelling or an infected-looking bite needs a check too. Most bites just itch for a few days.
Protecting your pets.
Talk to your vet about year-round prevention. Refresh pet water bowls daily, dump saucers after San Mateo's summer storms, and keep animals inside until a yard treatment dries. Heartworm reaches dogs through mosquito bites, and cats can get it as well; San Mateo's June–October season is long enough that most vets advise year-round prevention.
What a treatment visit looks like.
The tech walks the yard first. They dump or treat standing water. Larvicide goes in water you can't drain. Then they spray shady shrubs, where adults rest. Most plans repeat every three to four weeks. A visit usually takes 20 to 45 minutes.
Rain barrels and ponds.
- Pool covers: drain standing water after rain. - 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.
Questions to ask before you sign.
- When can kids and pets go back outside? - 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?
What affects the price
- Travel distance from the company's base.
- Commercial or multi-unit property.
- Gutter cleaning or drainage fixes bundled in.
- Standing water requiring larvicide.
- Special-event timing and rush scheduling.
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What's your biggest concern about mosquitoes?
When to call for help
Call if bites still keep you indoors. Dumping water should come first. early in the season, before the first big wave. Ponds, drains and dense shrubs are hard to handle yourself.
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 Mateo
San Mateo only gets about 21 inches of rain a year, so local mosquitoes breed where people add water: sprinklers, pools, fountains and AC drips. Summer highs around 78°F in San Mateo speed up the life cycle, and average humidity near 73% keeps adults active. In denser parts of San Mateo, storm drains, catch basins and gutters are big breeding spots. San Mateo has a mediterranean climate, and mosquitoes activity here tends to pick up late spring through early fall; year-round in the deep south. Across San Mateo, most of the housing is urban, so the usual entry points, moisture spots, and sheltered areas near the structure are what an inspection checks first. Across San Mateo, take a minute to note where you have seen activity and when it appears, so the inspection is faster and the quote more accurate. A local provider who knows San Mateo and California can point out the specific conditions that matter most here before you commit to a plan. Across San Mateo, before you book, ask whether the inspection is included, what the treatment plan covers, how many visits to expect, and what the written quote includes. Across San Mateo, getting the scope, the prep steps, and any follow-up terms in writing makes it much easier to compare providers fairly, and a good provider will walk you through each of these without pressure.
Local research
Mosquitoes in San Mateo, 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 Mateo, 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 Mateo
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
- Book barrier treatments before the season starts.
- Wear DEET or picaridin repellent outdoors.
- Drain kiddie pools when playtime ends.
- Flush tree holes or fill them with sand.
- Run a fan on the patio at dusk.
- Trim shrubs and ivy to reduce resting cover.
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?
Over 3,500 mosquito species exist worldwide
Tiger mosquitoes arrived in used tires in the 1980s
Questions people ask
Is mosquito spraying safe for pets, kids, and bees?
Applied by the label, it's considered low risk once dry. Keep kids and pets inside until it dries. Ask them to avoid flowers.
What if the mosquitoes are coming from my neighbor's property?
That's common. Treat your own yard and talk to your neighbor. Your local mosquito control district or health department can also help.
What are In2Care stations and do they work?
They're small water traps. Mosquitoes visit, then carry larvicide to other water. They work best against container breeders like tiger mosquitoes.
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 is the difference between larvicide and barrier spray?
It stops larvae from maturing. Barrier spray goes on leaves where adults rest. Most plans use both.
Do mosquitoes really change how people use their yards?
Across San Mateo, mosquito control works by removing standing water, treating the water that cannot be drained, and applying barrier treatments where adults rest. Across San Mateo, because they keep breeding through the season, an ongoing plan usually works best.
When is mosquito season in San Mateo?
It runs from about March into November. Daytime biters are tiger mosquitoes; evening biters are usually house mosquitoes.
Do mosquitoes in San Mateo carry West Nile?
They can. West Nile is found in every lower-48 state, California included. Cases usually peak in late summer. Repellent and dumping standing water are your best protection.
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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