The short version
Around Boulder, queens start nests in May, 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 Boulder with a nest near a door, deck or play area.
What to look for
Late-summer colonies are big and quick to sting. Near a door or deck, stings will happen. Wasps defend the area around their nest.
- 1Wasps disappearing into a hole in the lawn or a wall.
- 2Wasps entering an attic vent, dryer vent or weep hole.
- 3A soft or discolored patch of drywall with faint buzzing.
- 4Grey, papery football-shaped nest hanging in a tree or eave.
- 5Dead wasps collecting on interior windowsills in late summer.
- 6Wasps flying straight lines to and from one spot.
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
Expect a pro to check eaves, vents, sheds and the ground. Multiple nests are common late in the season.
- Time
- 45–75 minutes
- Best for
- Every job; species and nest location decide the method
Preventive Spring Treatment and Follow-Up
$150–$400
Prevention won't stop every nest, and no honest company in Boulder will say it does. It cuts the odds and catches nests that start early.
- Time
- 45–90 minutes
- Best for
- Repeat nests, or someone allergic to stings
Sealing Up After the Nest Is Dead
$150–$450
This is the step homeowners skip most often. Sealing the void after treatment keeps the next colony out.
- Time
- 1–2 hours
- Best for
- Closing soffits, vents and gaps once a void nest is dead
Ground and Wall-Void Nest Treatment
$150–$500
Ground nests can hold thousands of yellowjackets by late summer. Mowing over one sets them off. Treatment is done in protective gear, usually at dusk.
- Time
- 30–60 minutes plus a return visit
- Best for
- Yellowjackets in lawns, retaining walls, soffits and wall voids
Prices are typical published ranges. Ask what’s included before you compare quotes.
Yellowjackets often nest in old rodent holes and gaps in garden walls. Watch for wasps flying low and steady into one spot.Which wasps live around Boulder.
Paper wasps are the most common around Boulder. They build open, umbrella-shaped combs under eaves and railings. Western yellowjackets nest in the ground and in wall voids. They cause most stings. Bald-faced hornets build big gray nests in trees and eaves. Mud daubers build tube-shaped mud nests. They rarely sting.
Local wasps conditions in Boulder.
Boulder sits in a semi-arid climate, and that sets the pace for wasp activity here: mid-summer through fall (July-October). In Boulder, 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. An inspection in Boulder usually starts outside and works inward, checking the foundation, gaps around doors and windows, and any moisture or clutter near the structure first. Knowing Boulder'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 Boulder and Colorado 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.
Yellowjackets sometimes nest in attics and wall voids, getting in through a torn vent screen or a gap in the soffit. Buzzing in a ceiling is worth a look.When they’re most active.
Nests die back after the first hard freeze in fall. Early spring is the easiest time to remove small starts.
Where they nest around houses here.
Plenty of homes in Boulder have basements, but most nests are higher up. Check eaves, attic vents and window frames. Watch for traffic in and out of gaps. A ground nest looks like wasps streaming from one hole. Homes from Boulder out to Broomfield and Longmont share the same favorite nest spots.
A year of wasps in Boulder.
- Winter: lows near 20°F in Boulder. Nests die; only queens survive. - Late summer: peak season. Workers hunt sweets near people. - Summer: highs near 86°F in Boulder help colonies grow fast. - Spring: queens start new nests around May. Knock down small starts.
Wasp, hornet or bee?
- Honey bee: fuzzy and golden. about relocation. - Mud dauber: thin waist, mud tube nests. Rarely stings. - Hornet: larger, with a big closed paper nest. - Yellowjacket: bright yellow and black, nests in the ground. - Paper wasp: slim, long legs, open comb.
If you get stung.
If someone carries an epinephrine pen, use it. 911 for trouble breathing or a swollen face or throat. An antihistamine can ease itching and swelling. Wash the sting and use a cold pack. Move away from the nest first.
Keeping wasps away from the patio.
- Gaps: seal gaps after a nest is gone. - Spring checks: knock down small nests early. - Fruit: pick up fallen fruit. - Trash: keep lids tight and bins away from doors. - Food: cover plates and drinks outdoors.
Ground nests: what to do.
Pros treat ground nests at night, when the colony is home. Don't pour gasoline or water in. Don't mow over it. Keep kids and pets away. Mark the hole with a flag.
A nest, or just visitors?
Follow the line back to an eave, vent, shrub or hole. Watch at dusk, when they fly home. A nest shows steady traffic to one spot. Wasps on flowers or trash cans may come from far away.
Treating a small nest yourself, safely.
- Leave it overnight, then bag the nest. - Never spray from a ladder. - Use a jet wasp spray from several feet away. - Wear long sleeves, pants and gloves. - Wait until dusk, when wasps are home and slow. - Never if anyone in the house is allergic. - Only if it’s small, low and out in the open.
Wasps and pets.
Keep pet food and water bowls indoors in late summer. your vet if the throat swells or breathing changes. Most stings just swell a little. Dogs often snap at wasps and get stung on the face.
Kids and wasps.
Use cups with lids for sweet drinks outside. Check play sets, slides and playhouses for nests each spring. Swatting makes a sting more likely. Teach kids to walk away calmly.
After the nest is gone.
Knock down small new nests early next spring. Check nearby eaves for new starts. Seal the gap a wall nest used once it's quiet. Wasps don't reuse old nests.
Wasps at picnics and barbecues.
- Kids: teach them to walk away calmly. - Calm: don’t swat; slowly move away. - Trash: bag scraps and close the bin. - Food: keep it covered until you eat. - Drinks: use cups with lids or straws.
Ground nests in the lawn.
Mark it, and keep mowers and kids away until it's treated. Watch for wasps flying in and out of the grass. Yellowjackets often nest in old rodent holes.
Questions to ask before you sign.
- Is a return visit included? - Is removal of the dead nest included? - How will you treat a nest inside the wall? - What kind of wasp is it?
What affects the price
- Whether nest removal is included after treatment.
- Return visit to confirm a void nest is dead.
- Roof pitch and safe access to the nest location.
- Open comb, or hidden in a wall.
- Ground nest with multiple entrances or deep burrows.
- Colony size, which climbs sharply from June to September.
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What's your biggest concern about wasps?
When to call for help
Call for nests in walls, attics, the ground, or anywhere high. right away if anyone in the house is allergic. Don't seal a hole wasps are using. They'll find another way in.
What you can do yourself
Big, high or hidden nests are a job for a pro. Knock it down the next day. Spray it at dusk with a wasp aerosol. A small, reachable paper wasp nest is a fair DIY job.
Wasps in Boulder
In denser parts of Boulder, nests turn up in eaves, balconies, signs and wall gaps. Winter lows near 20°F in Boulder end the season; only new queens survive, tucked into sheltered spots. With summer highs near 86°F in Boulder, colonies grow fast and are biggest by August.
Local research
Wasps in Boulder, CO: what the public record shows
Before you compare quotes, it helps to know which wasps actually live in Colorado, when they are busiest around Boulder, and what the state figures look like. Everything below links to the agency or university page it came from.
Wasp species recorded in Colorado
- 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…
- 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…
- Native paper wasps (Polistes spp. (e.g., P. fuscatus, P. apachus, P. exclamans)) — Open umbrella-shaped nests under eaves, porch ceilings and railings. UC IPM: paper wasp colonies 'vary between 15 to 200 individuals'; Penn State: queens 'establish nests in May…
When wasps are busiest around Boulder
CSU: European paper wasp 'earliest activity is sometimes seen in the first half of March'; 'Individual colonies are established anew each spring' and 'may contain several dozen individuals by the end of summer'. Western yellowjacket colonies die each fall (USU).
CSU: European paper wasp is 'very abundant in every urbanized county in eastern Colorado and the three western Colorado counties of Mesa, Montrose, and Delta'; nests in 'outdoor grills, large bells, pipes, rock cavities, and hollow spaces behind walls'.
Rules that apply in Colorado
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: Colorado State University Extension; CDC MMWR; Yellowjackets and Other Social Wasps (Pest Notes); Baldfaced Hornet; European Paper Wasp. Figures are quoted as the source prints them. How we check our sources
Simple ways to keep wasps away
- Check sheds and garages for nests each May.
- Store pet food indoors and clean bowls after meals.
- Screen attic, gable and dryer vents with fine mesh.
- Fill gaps in retaining walls and stacked stone.
- Walk the eaves in April and knock down starter nests.
A good wasp quote names the species, where the nest is, how it will be treated and whether taking it down or sealing the gap is included.Did you know?
European hornets hunt at night and are drawn to porch lights
Mud daubers stock their nests with paralyzed spiders
Questions people ask
How do I find a good wasp control company?
Check that they're licensed in Colorado. Ask how they treat hidden nests and whether removal is included.
Should I be worried about a nest in the ground?
Mowing over them sets them off. Ground nests are usually yellowjackets. Yes, if it's near a path or play area.
Can I seal the hole wasps are using?
Treat first, then seal once activity stops. They may chew into your house. Sealing traps them inside. No.
Can I just leave the nest alone until winter?
If it's out of the way, often yes. Around Boulder, nests die back after the first hard freeze in fall.
Wasp or bee: does it matter?
It matters because honey bees can often be relocated. Bees are fuzzy and rounder. Wasps are smooth and narrow-waisted.
How seriously do people take wasp problems?
In Boulder, most people act once a nest is near a door, deck or play area, where stings are most likely.
How common are wasp sightings?
In Boulder, very common in late summer, when colonies peak and wasps go looking for sweet food.
When is wasp season in Boulder?
Around Boulder, queens start nests in May, and colonies peak in late summer. Nests die back after the first hard freeze in fall.
Are hornets common in Boulder?
Bald-faced hornets are, in trees and on eaves. Most stings come from yellowjackets, though.
Nearby cities
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Sources (8)
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