The short version
Around San Mateo, queens start nests in April, and colonies peak in late summer. Small, low paper wasp nests can be handled at dusk. Leave wall, ground and high nests to a pro.
- Treat nests at dusk, when wasps are home.
- Never seal a hole wasps are using.
- Ground and wall nests are best left to a pro.
- Knock down small nests early in spring.
- Call 911 for breathing trouble after a sting.
Homeowners and renters in San Mateo with a nest near a door, deck or play area.
What to look for
Wasps defend the area around their nest. Near a door or deck, stings will happen. Late-summer colonies are big and quick to sting.
- 1Wasps disappearing into a hole in the lawn or a wall.
- 2Wasps appearing indoors near light fixtures or windows.
- 3Sudden wasp interest in overripe fruit under a tree.
- 4Large wasps circling porch lights after dark.
- 5Wasps hovering at a mulch bed or retaining wall gap.
- 6Grey, papery football-shaped nest hanging in a tree or eave.
Why it’s worth acting soon
- Nests grow all summer.
- Ground nests get disturbed by mowing.
- Wall nests can chew through into rooms.
- Stings are dangerous for anyone allergic.
Treatment options and typical costs
Inspection and Nest Identification
$75–$200
A pro starts by confirming the species and the nest location. Paper wasps, hornets and yellowjackets each call for a different approach.
- Time
- 45–75 minutes
- Best for
- Every job; species and nest location decide the method
Preventive Spring Treatment and Follow-Up
$150–$400
Preventive work makes the most sense for San Mateo homes that have had nests two years running, or where someone has a sting allergy. It is a modest cost compared with a wall-void job.
- Time
- 45–90 minutes
- Best for
- Homes with repeat nests or a sting allergy in the household
Ground and Wall-Void Nest Treatment
$150–$500
Expect a return visit for void nests around San Mateo homes, because dust works over several days rather than minutes. The follow-up confirms the colony is finished before sealing.
- Time
- 30–60 minutes plus a return visit
- Best for
- Yellowjackets in lawns, retaining walls, soffits and wall voids
Sealing Up After the Nest Is Dead
$150–$450
Sealing gaps around San Mateo homes also blocks other pests, so the work pays twice. Screened vents and tight soffits also keep out birds and bats.
- Time
- 1–2 hours
- Best for
- Sealing soffits, vents and gaps after a wall nest has died
Prices are typical published ranges. Ask what’s included before you compare quotes.
Once a nest is dead, screening and sealing gaps around pipes and vents keeps next year's queen from using the same opening.Which wasps live around San Mateo.
Bald-faced hornets build big gray nests in trees and eaves. In mild winters around San Mateo, some yellowjacket nests survive and grow huge. Leave those to a pro. Mud daubers build tube-shaped mud nests. They rarely sting. Paper wasps are the most common around San Mateo. They build open, umbrella-shaped combs under eaves and railings. Western yellowjackets nest in the ground and in wall voids. They cause most stings.
Local wasps conditions in San Mateo.
An inspection in San Mateo 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 Mateo'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 Mateo 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. San Mateo sits in a mediterranean climate, and that sets the pace for wasp activity here: mid-summer through fall (July-October). For San Mateo homes, the area is mostly urban, so wasps 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.
Paper wasps like quiet, sheltered corners. Check garage rafters, door tracks and high shelves in spring for small starter combs.When they’re most active.
Nests die back with the first hard freeze, around November. Early spring is the easiest time to remove small starts.
Where they nest around houses here.
Watch for traffic in and out of gaps. A ground nest looks like wasps streaming from one hole. Homes from San Mateo out to San Francisco and Oakland share the same favorite nest spots. Plenty of homes in San Mateo have basements, but most nests are higher up. Check eaves, attic vents and window frames.
A year of wasps in San Mateo.
- Summer: highs near 78°F in San Mateo help colonies grow fast. - Late summer: peak season. Workers hunt sweets near people. - Winter: lows near 43°F in San Mateo. Some nests keep going. - Spring: queens start new nests around April. Knock down small starts.
Wasp, hornet or bee?
- Yellowjacket: bright yellow and black, nests in the ground. - Hornet: larger, with a big closed paper nest. - Mud dauber: thin waist, mud tube nests. Rarely stings. - Honey bee: fuzzy and golden. about relocation. - Paper wasp: slim, long legs, open comb.
If you get stung.
An antihistamine can ease itching and swelling. 911 for trouble breathing or a swollen face or throat. If someone carries an epinephrine pen, use it. Move away from the nest first. Wash the sting and use a cold pack.
Keeping wasps away from the patio.
- Trash: keep lids tight and bins away from doors. - Fruit: pick up fallen fruit. - Spring checks: knock down small nests early. - Gaps: seal gaps after a nest is gone. - Food: cover plates and drinks outdoors.
Ground nests: what to do.
Don't mow over it. Don't pour gasoline or water in. Pros treat ground nests at night, when the colony is home. Mark the hole with a flag. Keep kids and pets away.
A nest, or just visitors?
Watch at dusk, when they fly home. Follow the line back to an eave, vent, shrub or hole. Wasps on flowers or trash cans may come from far away. A nest shows steady traffic to one spot.
Treating a small nest yourself, safely.
- Never if anyone in the house is allergic. - Wait until dusk, when wasps are home and slow. - Wear long sleeves, pants and gloves. - Use a jet wasp spray from several feet away. - Never spray from a ladder. - Leave it overnight, then bag the nest. - Only if it’s small, low and out in the open.
Wasps and pets.
your vet if the throat swells or breathing changes. Keep pet food and water bowls indoors in late summer. Dogs often snap at wasps and get stung on the face. Most stings just swell a little.
Kids and wasps.
Check play sets, slides and playhouses for nests each spring. Use cups with lids for sweet drinks outside. Teach kids to walk away calmly. Swatting makes a sting more likely.
After the nest is gone.
Check nearby eaves for new starts. Knock down small new nests early next spring. Wasps don't reuse old nests. Seal the gap a wall nest used once it's quiet.
Wasps at picnics and barbecues.
- Food: keep it covered until you eat. - Trash: bag scraps and close the bin. - Calm: don’t swat; slowly move away. - Kids: teach them to walk away calmly. - Drinks: use cups with lids or straws.
Ground nests in the lawn.
Watch for wasps flying in and out of the grass. Mark it, and keep mowers and kids away until it's treated. Yellowjackets often nest in old rodent holes.
Questions to ask before you sign.
- How will you treat a nest inside the wall? - Is removal of the dead nest included? - Is a return visit included? - What kind of wasp is it?
What affects the price
- Whether nest removal is included after treatment.
- Local labor rates and seasonal demand.
- Ground nest with multiple entrances or deep burrows.
- Sealing gaps after the nest is dead.
- Dense siding, brick or stone that limits dust access.
- Species: paper wasps cost least, hornets and yellowjackets more.
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What's your biggest concern about wasps?
When to call for help
Don't seal a hole wasps are using. They'll find another way in. Call for nests in walls, attics, the ground, or anywhere high. right away if anyone in the house is allergic.
What you can do yourself
A small, reachable paper wasp nest is a fair DIY job. Spray it at dusk with a wasp aerosol. Knock it down the next day. Big, high or hidden nests are a job for a pro.
Wasps in San Mateo
With summer highs near 78°F in San Mateo, colonies grow fast and are biggest by August. Winter lows near 43°F in San Mateo are mild, so some yellowjacket nests survive the winter and keep growing. In denser parts of San Mateo, nests turn up in eaves, balconies, signs and wall gaps.
Local research
Wasps in San Mateo, CA: what the public record shows
Before you compare quotes, it helps to know which wasps 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.
Yellowjacket colony size (UC IPM)
A mature nest inside a wall void can hold thousands of workers.
UC Statewide IPM ProgramPaper wasp colony size (UC IPM)
Paper wasp nests under eaves are small and usually a quick single-visit job.
UC Statewide IPM ProgramWasp species recorded in California
- Western yellowjacket (Vespula pensylvanica) — UC IPM: 'the most commonly encountered species and is sometimes called the "meat bee"' in California and the Western states; ground and wall-void nester and aggressive scavenger…
- German yellowjacket (Vespula germanica) — UC IPM: 'becoming more common in many urban areas of California, where it frequently nests in houses.' Named among Ohio's three main species (German, Eastern, Common yellowjacke…
- Bald-faced hornet (Dolichovespula maculata) — Penn State: 'found in most of the 48 contiguous states and D.C., throughout Canada and in Alaska'; actually an aerial yellowjacket that builds the football-shaped gray paper nes…
- European paper wasp (Polistes dominula) — Penn State: 'first reported in 1978 around Boston', now 'coast to coast ... although they are apparently less common in the Southeast and Great Plains'; nests in 'eaves of struc…
When wasps are busiest around San Mateo
Queens emerge in late winter to early spring, nests grow from spring to midsummer and peak in late summer; in coastal California south of San Francisco some yellowjacket colonies survive several years and become very large (UC IPM).
UC IPM: the western yellowjacket is the most commonly encountered species ('meat bee'); the German yellowjacket 'is becoming more common in many urban areas of California, where it frequently nests in houses.' Paper wasps (Polistes fuscatus aurifer, P. apachus, P. dominula) prefer orchards and vineyards.
Rules that apply in California
For context, nationally
- 788 — Deaths from hornet, wasp, and bee stings, 2011–2021 (US). CDC MMWR
- 72 deaths per year — Average annual sting deaths, 2011–2021 (US). CDC MMWR
Sources: Yellowjackets and Other Social Wasps (Pest Notes); CDC MMWR; Baldfaced Hornet; European Paper Wasp. Figures are quoted as the source prints them. How we check our sources
Simple ways to keep wasps away
- Caulk around cable, gas and conduit entry points.
- Cover drinks outdoors and use lidded cups for kids.
- Seal soffit seams and fascia gaps before spring.
- Mow at dawn when ground-nesting wasps are sluggish.
- Walk the eaves in April and knock down starter nests.
Jot down where nests turned up this year. Queens often pick the same eaves and gaps, so you'll know where to look first next spring.Did you know?
European hornets hunt at night and are drawn to porch lights
Yellowjacket nests are never reused a second year
Questions people ask
Can I just leave the nest alone until winter?
If it's out of the way, often yes. Around San Mateo, nests die back with the first hard freeze, around November.
Do wasp traps work?
They catch some yellowjackets, but rarely fix a nest problem. Place them away from where people sit.
How do I know if I have wasps, hornets or yellowjackets?
Paper wasps build open, umbrella-shaped combs. Yellowjackets nest in the ground or walls. Hornets build big, gray, closed nests.
Why are there suddenly so many wasps in late summer?
Colonies are at their biggest by late summer. Food gets scarce, so workers hunt sweets and protein near people.
Wasp or bee: does it matter?
Wasps are smooth and narrow-waisted. Bees are fuzzy and rounder. It matters because honey bees can often be relocated.
How often should you check your property for wasp nests?
Every week or two from spring through late summer. For San Mateo homes, look under eaves, decks, sheds and play equipment, where small nests are easy to deal with.
Are hornets common in San Mateo?
Bald-faced hornets are, in trees and on eaves. Most stings come from yellowjackets, though.
Nearby cities
Related guides
Sources (9)
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 Wasp Exterminator · Updated September 11, 2026 · How we write these guides