The short version
Around Longmont, flies are busiest from about April into October. Find their source: trash, drains, compost or a dead animal. Remove it, then seal gaps and screens.
- Flies breed in something nearby.
- Check trash, drains and compost first.
- Tape a drain overnight to test it.
- Big shiny flies can mean a dead animal.
- Screens and door sweeps keep them out.
Anyone in Longmont who wants flies out of the house.
What to look for
Spraying the flies you see won't stop new ones. In summer heat, eggs become adults in about a week. They breed in something nearby. Flies don't come from nowhere.
- 1Flies gathering at sunny windows.
- 2Tiny fuzzy flies near sinks and drains.
- 3Shiny green or blue flies indoors.
- 4Maggots in trash bins.
- 5Flies around compost or pet waste.
- 6A sudden bad smell with flies.
Why it’s worth acting soon
- Flies carry germs onto food and counters.
- Populations grow fast in warm weather.
- A dead animal smell gets worse.
- Cluster flies return every fall.
Treatment options and typical costs
Source Inspection and Fly Identification
$75–$200
Around Longmont, an inspection covers the kitchen, bathrooms, basement, garage and the exterior dumpster or bin area. Sticky monitors may be left to map activity.
- Time
- 45–90 minutes
- Best for
- Every job; the species points to the breeding site
Exclusion: Screens, Door Sweeps and Air Curtains
$150–$450 (air curtains more)
Exclusion is the part of fly control in Longmont that keeps working without anyone thinking about it. Screens and sweeps do not need refilling or replacing every month.
- Time
- 1–4 hours
- Best for
- Buildings with steady fly entry from outside
Light Traps, Baits and Residual Resting-Surface Treatment
$150–$450
For adults inside, light traps and baits can help. This buys time while the source is fixed.
- Time
- 1–2 hours
- Best for
- Knocking down adults while sources are fixed
Cluster-Fly Void Treatment, Sealing and Follow-Up Monitoring
$150–$500; follow-ups $50–$150
Restaurants and multifamily buildings in Longmont usually go on a monthly or quarterly plan. Drains, trash areas and traps are rechecked each time.
- Time
- 1–3 hours, plus scheduled checks
- Best for
- Cluster flies each fall; ongoing checks for commercial sites
Prices are typical published ranges. Ask what’s included before you compare quotes.
Drain flies breed in the slime inside drains. A stiff brush and an enzyme cleaner clear it.Which flies show up around Longmont.
Fungus gnats hover around overwatered houseplants. They show up at windows on warm days. Cluster flies hide in attics and walls around Longmont for winter. A sudden swarm often means something died nearby. Blow flies are shiny green or blue. They breed in the slime inside drains. Drain flies are tiny and fuzzy. They breed in trash, compost and manure. House flies are the most common around Longmont.
Local flies conditions in Longmont.
A provider who works Longmont 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. Knowing Longmont'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. An inspection in Longmont usually starts outside and works inward, checking the foundation, gaps around doors and windows, and any moisture or clutter near the structure first. Around Longmont, the area is mostly suburban, so flies 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. Longmont sits in a semi-arid climate, and that sets the pace for fly activity here: spring through fall; cluster flies overwinter indoors.
Trash bins are the top source in summer. Keep lids closed and rinse bins every week or two.Fly season in Longmont.
Numbers peak in mid to late summer. Cluster flies move into walls in fall. Seal gaps before September.
Finding the source.
From Longmont out to Boulder and Loveland, trash bins in summer are the usual culprit. Likely a dead animal. Bad smell plus big shiny flies? Flies stuck to it mean the drain is the source. Tape over a drain overnight. Check trash bins, recycling and compost first. Watch where flies gather and where they're coming from.
A year of flies in Longmont.
- Spring: flies return. Check screens. - Summer: peak season in Longmont. Empty trash twice a week. - Fall: cluster flies look for a way in. Seal gaps. - Winter: fix screens and doors.
Which fly is it?
- House fly: gray, a quarter inch, everywhere. - Drain fly: tiny, fuzzy, moth-like wings. - Blow fly: shiny green, blue or bronze. - Cluster fly: big, slow, golden hairs. - Fungus gnat: tiny and black, near plants. - Fruit fly: tan with red eyes, near ripe fruit.
Cleaning a drain fly drain.
- Scrub: run a stiff brush down the drain. - Enzyme: pour in an enzyme drain cleaner at night. - Repeat: do it daily for a week. - Check: tape over the drain to see if flies still emerge. - Skip: bleach alone doesn’t clear the slime.
Keeping flies out.
- Screens: patch holes in windows and doors. - Sweeps: add door sweeps to exterior doors. - Trash: keep lids closed and rinse bins. - Compost: cover it and keep it away from doors. - Pets: pick up waste daily.
Fly traps that actually help.
- Sticky ribbons: fine for garages and sheds. - UV light traps: best for kitchens and businesses. - Bait traps: hang them outside, away from doors. - Swatter: still works for a few strays. - Skip: bug bombs. They don’t reach the source.
If something died nearby.
Follow the smell and the flies. Wear gloves, bag it, and disinfect the spot. A wall may need a small hole opened. The flies stop once the source is gone.
Flies and pets.
Pet food and waste draw flies fast. Pick up food bowls after meals. Clean up the yard daily in summer. Flies biting a dog's ears are usually stable flies. Ask your vet about protection.
Flies at a business.
Restaurants and food businesses need a steady routine. Seal dumpsters and clean them weekly. Use air curtains or strip doors at busy entries. Schedule drain cleaning and regular service visits.
Flies and food safety.
Flies land on trash and then on food. Cover food outdoors and wipe counters often. Throw out food flies have landed on for long. Keep fruit in the fridge in summer.
What a fly visit looks like.
The tech looks for the source first. They check trash areas, drains, attics and gaps by doors. Then they clean, seal or treat what they find. Traps help confirm the problem is gone.
Screens and doors.
- Screens: patch holes and check the corners. - Doors: add sweeps and keep them closed. - Patio doors: a screen door helps in summer. - Fans: a fan by the door keeps flies moving on.
Compost and yard waste.
Flies breed in wet, rotting material. Keep compost covered and turn it often. Bag clippings. Pick up fruit and pet waste every few days.
Trash day habits.
Bag food scraps tightly before they go in the bin. Rinse bins every couple of weeks in warm weather. Keep lids shut and park bins away from doors.
Questions to ask before you sign.
- What kind of fly is it? - Where are they breeding? - What will you clean, seal or treat? - Are follow-up visits included? - Is dead animal removal extra?
What affects the price
- Opening and repairing a wall or ceiling void.
- Number and type of light traps installed.
- Follow-up visits and monitor replacement.
- Home versus restaurant or multifamily building.
- Travel distance and local labor rates.
- Screens, door sweeps and sealing work required.
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What bothers you most about flies?
When to call for help
if cluster flies come back every fall. Businesses usually need regular service. Call if you can't find the source after a few days. if you smell something dead in a wall.
What you can do yourself
A pro helps with hidden sources, walls and attics. Clean drains, rinse bins and fix screens. Find the source and remove it. Most home fly problems are DIY.
Flies in Longmont
In Longmont's neighborhoods, the usual sources are trash bins, compost, pet waste and drains. With about 14 inches of rain a year, damp spots around Longmont also breed small flies. Summer highs near 88°F in Longmont speed up the fly life cycle, so trash and compost need extra care.
Fly tips from the experts
Where are the flies coming from?
The kind of fly tells you where to look. Around Longmont, Colorado, note its size, where it gathers and when it shows up. Then go after the source.
Small flies near drains
Tiny, fuzzy flies near a sink or shower usually breed in the slimy film inside the drain. Scrub the drain with a stiff brush. Spraying the adults won’t stop them.
UC IPM: drain fliesHouse flies around doors and trash
House flies breed in garbage, pet waste and rotting plants. Clear those out first, then add screens and keep doors closed. Traps help, but they don’t fix the source.
EPA: managing fliesSlow flies at the windows in fall?
In colder states like Colorado, sluggish flies at upstairs windows in fall, winter or early spring are often cluster flies. They spend winter in attics and walls but don’t breed indoors. Sealing gaps outside in late summer keeps them out.
University of Minnesota Extension: fliesBased on guidance from university extension services and the EPA.
How we check our sourcesLocal research
Flies in Longmont, CO: what the public record shows
Before you compare quotes, it helps to know which flies actually live in Colorado, when they are busiest around Longmont, and what the state figures look like. Everything below links to the agency or university page it came from.
Most common fly in Colorado homes during cool months
Flies appearing indoors in fall and winter in Colorado are usually overwintering cluster flies from the lawn, not a sanitation problem.
Colorado State University ExtensionFly species recorded in Colorado
- House fly (Musca domestica) — Non-biting; breeds in manure, garbage, lawn clippings, decaying produce. 45 days at 60°F to 7 days at 95°F. Carries bacteria and viruses causing diarrhea, cholera, food poisonin…
When flies are busiest around Longmont
Cluster flies enter buildings late August–September and reappear on warm winter days; fruit fly numbers peak late summer and early fall.
CSU Extension notes cluster flies are particularly abundant at higher elevations in Colorado; the house fly is not the most common indoor fly in the state.
Sources: Colorado State University Extension; Texas A&M AgriLife Extension; University of New Hampshire Extension; Flies (Home and Landscape). Figures are quoted as the source prints them. How we check our sources
Simple ways to keep flies away
- Keep trash bins closed and rinse them.
- Take trash out often in summer.
- Repair window and door screens.
- Add door sweeps.
- Pick up pet waste daily.
- Clean drains with a brush and enzyme cleaner.
A good quote names the fly, the source, and what will be cleaned, sealed or treated.Did you know?
Drain flies are sometimes called moth flies
Fly specks on ceilings are regurgitated food and waste
Questions people ask
What kind of fly do I have?
Shiny green or blue: blow flies. Small and fuzzy near drains: drain flies. Big and slow at windows: cluster flies.
What should be in a fly control quote?
Fly type, source, what gets treated or sealed, and follow-ups.
Are fly control treatments safe for kids and pets?
Ask what product they use. Traps and sealing are the gentlest options. Used by the label, yes.
Do I need ongoing fly service?
Homes rarely do. Restaurants, farms and food businesses often need regular service.
Can flies come from my neighbor's property?
Your own trash and compost still matter most. House flies travel a mile or more. Yes.
What does professional fruit fly control cost?
Fruit flies are the least expensive fly problem to hand to a professional, at $100 to $175 in Local quotes vary; ask for a written estimate.
Do customers tell restaurants when they see a pest?
Around Longmont, flies are controlled by finding and removing the breeding source — the garbage, food, or moisture they are drawn to. Around Longmont, cleaning the source and setting traps handles the adults, and because flies reproduce quickly, source removal is the part that actually stops them.
Are cluster flies common in Longmont?
Yes, they're a fall and winter nuisance around Longmont. Seal gaps around windows and siding before September.
When is fly season in Longmont?
Flies are busiest from about April into October. Cluster flies also appear at windows in winter.
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Sources (13)
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 Fly Exterminator · Updated September 11, 2026 · How we write these guides