The short version
Around Boulder, mosquito season runs from about May through September. Treatment means removing water and treating what you can't drain. A barrier spray follows every few weeks.
- Dump standing water every week.
- Evening biters are usually house 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 Boulder tired of mosquito bites at home.
What to look for
In summer heat, eggs become biting adults in about a week. Mosquitoes breed in standing water, even a bottle cap's worth. Often the source is a neighbor's yard or a storm drain.
- 1Welts on ankles and calves after yardwork.
- 2Bites getting worse after each wet spell.
- 3Mosquitoes indoors resting on walls or in closets.
- 4Rain barrels without screens or lids.
- 5Wriggling larvae in birdbaths, buckets, or saucers.
- 6A neighbor's pool turning green and untended.
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 Boulder
Spring
dump water and clean gutters before May.
Summer
peak season in Boulder, especially July and August.
Fall
activity fades with cooler nights.
Winter
fix drainage and store containers upside down.
Treatment options and typical costs
Property Inspection for Breeding Sites
$0–$150 (often bundled with a first treatment)
Expect a written or verbal summary of what was found on your Boulder property, including problems on the neighbor's side of the fence. You cannot treat next door, but you can plan around it.
- Time
- 30–60 minutes
- Best for
- Every yard; finds where mosquitoes actually breed
Barrier (Residual) Yard Treatment
$75–$200 per visit; $350–$900 per season
Most programs use a pyrethroid spray from a backpack mister. It fades over three to four weeks. Repeat visits keep the coverage up through the season.
- Time
- 20–45 minutes per visit, repeated every 3–4 weeks
- Best for
- Shaded yards with shrubs, ivy, and dense landscaping
Monitoring and Seasonal Plans
$50–$150 per follow-up visit; $350–$900 per season bundled
Monitoring also catches new water sources, such as a kiddie pool left out or a gutter that clogged after a Boulder storm. Small changes like that undo a lot of work.
- Time
- 15–30 minutes per check; season runs spring through first frost
- Best for
- Anyone who wants the yard usable all summer
Misting Systems and In2Care-Style Stations
misting $2,000–$4,500 installed plus refills; stations $200–$500 per season
Expect a site walk before any install. Nozzle and station placement depend on the lot. Ask for the refill and service costs up front.
- 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.
A treatment visit covers the shaded plants and beds where adults rest, along with any standing water that can't be drained.How mosquito treatment works in Boulder.
Barrier spray covers shady shrubs and leaves. Larvicide handles water you can't drain, like ponds or drains. Around Boulder, the season runs from about May through September, so a plan usually starts in spring and runs to the end of the season. Then spray where the adults rest. First, find and remove the water where they breed. Treatment has two parts.
Which mosquitoes bite around Boulder.
They can travel a long way from where they hatch. Floodwater mosquitoes hatch in big waves after heavy rain or snowmelt. They're the main West Nile carriers. They breed in storm drains. House mosquitoes (Culex) bite from dusk into the night.
Mosquitoes that bite indoors usually slip in through gaps around doors or torn window screens.Mosquito season in Boulder.
Numbers usually peak in July and August. West Nile cases usually peak in late summer.
A year of mosquitoes in Boulder.
- Spring: dump water and clean gutters before May. - Winter: fix drainage and store containers upside down. - Fall: activity fades with cooler nights. - Summer: peak season in Boulder, especially July and August.
The weekly water walk.
- Saucers and pots: empty them or add sand. - Gutters: clear leaves so water drains. - Tree holes: fill them with sand. - AC drip lines and downspouts: make sure water drains away. - Pet bowls: refresh daily. - Birdbaths: change the water twice a week. - Tarps and covers: pull them tight so water runs off. - Toys and buckets: store them upside down.
Avoiding bites.
- Clothing: long sleeves and pants help at dusk. - Repellent: DEET, picaridin, IR3535 or oil of lemon eucalyptus. - Timing: tiger mosquitoes bite by day; house mosquitoes at dusk. - Screens: repair holes in window and door screens. - Fans: a patio fan keeps weak-flying mosquitoes away.
Low-cost ways to cut mosquitoes.
- Mosquito fish: they eat larvae in ornamental ponds. - Mosquito dunks: Bti tablets kill larvae in rain barrels and ponds. - Lights: yellow bug lights attract fewer insects to the porch. - Trimming: thin out dense shrubs and tall grass. - Pumps and fountains: moving water breeds far fewer mosquitoes.
Mosquito or look-alike?
- Non-biting midges: swarm near water at dusk. Harmless, just annoying. - Crane flies: look like giant mosquitoes. They don’t bite. - Mosquitoes: slim, long legs, and a needle-like mouth. - No-see-ums: tiny biting gnats near marshes. Screens need a finer mesh.
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.
Talk to your vet about year-round prevention. Heartworm reaches dogs through mosquito bites, and cats can get it as well; in Boulder the main exposure runs July through September. Refresh pet water bowls daily, dump saucers after Boulder's summer storms, and keep animals inside until a yard treatment dries.
What a treatment visit looks like.
They dump or treat standing water. The tech walks the yard first. A visit usually takes 20 to 45 minutes. Most plans repeat every three to four weeks. Then they spray shady shrubs, where adults rest. Larvicide goes in water you can't drain.
Rain barrels and ponds.
- Ponds: fish and moving water keep larvae down. - Barrels: cover openings with fine mesh. - Pool covers: drain standing water after rain. - Tarps: shake out any that hold rainwater. - Gutters: clear them so water drains away. - Bird baths: change the water every few days.
Questions to ask before you sign.
- How often will you come? - What product will you spray? - When can kids and pets go back outside? - How do you protect bees and flowers? - What happens if bites come back between visits? - Do you treat standing water too?
What affects the price
- Local labor rates and licensing costs.
- Ponds, creeks, or wetland edges on the property.
- Amount of shade and dense vegetation.
- Special-event timing and rush scheduling.
- Re-treatment policy between scheduled visits.
- Synthetic versus botanical barrier products.
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What's your biggest concern about mosquitoes?
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 Boulder
Around Boulder, 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. Around Boulder, 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 Boulder and Colorado can point out the specific conditions that matter most here before you commit to a plan. Around Boulder, 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. Around Boulder, 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. Boulder only gets about 20 inches of rain a year, so local mosquitoes breed where people add water: sprinklers, pools, fountains and AC drips. Summer highs around 86°F in Boulder speed up the life cycle. In denser parts of Boulder, storm drains, catch basins and gutters are big breeding spots. Boulder has a semi-arid climate, and mosquitoes activity here tends to pick up late spring through early fall; year-round in the deep south.
Local research
Mosquitoes in Boulder, CO: what the public record shows
Before you compare quotes, it helps to know which mosquitoes 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.
West Nile neuroinvasive disease cases, 2024
Neuroinvasive counts are the most reliable state comparison because nearly all severe cases are diagnosed and reported.
CDCWhen mosquitoes are busiest around Boulder
CDC: West Nile transmission June through October, peaking late August to early September. Illinois found its first positive mosquito batch of 2025 on May 9, so larval control should start in May.
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. Figures are quoted as the source prints them. How we check our sources
Simple ways to keep mosquitoes away
- Empty plant saucers after every rain.
- Tighten lids on trash and recycling bins.
- Wear DEET or picaridin repellent outdoors.
- Drop Bti dunks in water you cannot drain.
- Dump and scrub birdbaths every week.
- Keep pools chlorinated and covered when unused.
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?
Mosquitoes home in on carbon dioxide from breath
Over 3,500 mosquito species exist worldwide
Questions people ask
What does a mosquito inspection involve?
They also check shady spots where adults rest. Gutters, saucers, tarps and low spots get checked first. The tech walks the yard looking for standing water.
Can I get rid of mosquitoes permanently?
They fly in from nearby. Removing water and spraying resting spots cuts them down a lot. Not completely.
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?
Barrier spray goes on leaves where adults rest. Most plans use both. It stops larvae from maturing.
Will mosquito treatment kill bees and butterflies?
Ask them to skip blooming plants. Spraying when bees rest helps too. It can if spray hits flowers.
Do store-bought mosquito products actually work?
Around Boulder, dIY sprays and foggers give temporary relief, but they do not stop the next generation from breeding in the standing water nearby. Around Boulder, the most effective DIY step is removing the water, and professional larvicide and barrier treatments handle the rest.
When is mosquito season in Boulder?
It runs from about May through September.
Do mosquitoes in Boulder carry West Nile?
Cases usually peak in late summer. Repellent and dumping standing water are your best protection. They can. West Nile is found in every lower-48 state, Colorado included.
Nearby cities
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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