The short version
Most spiders in Longmont are harmless. Black widows live here, as in every lower-48 state. Longmont is outside the brown recluse range, so most 'recluses' here are look-alikes. Identify first, then treat.
- Most house spiders are harmless.
- Black widows live in every lower-48 state.
- Brown recluses don’t live here.
- Skip foggers; they don’t reach hiding spots.
- Yellow bug lights and door sweeps help a lot.
Anyone in Longmont who's spotted a spider and wants to know if it matters.
What to look for
Most are harmless and even helpful. Webs and egg sacs keep the cycle going. Spiders follow their food. More insects means more spiders.
- 1Fresh cobwebs in corners days after cleaning them.
- 2Dead insects wrapped in silk along ledges.
- 3Spiders in bathtubs and sinks in late summer.
- 4Spiders wandering across walls at night.
- 5Webs across doorways or gates each morning.
- 6Silk strands stretched across windows after wind.
Why it’s worth acting soon
- Egg sacs hatch hundreds of spiderlings.
- Webs build up in eaves, corners and garages.
- Widows nest under outdoor furniture and grills.
Treatment options and typical costs
Inspection and Species Identification
$75–$200
The spiders found in most Longmont homes are harmless house spiders, cellar spiders or orb weavers. A careful look in Longmont separates those from a black widow or, where they occur, a brown recluse.
- Time
- 45–90 minutes
- Best for
- Every job; the species decides how much to do
Web and Egg-Sac Removal
$100–$250
Across Longmont, this step usually covers the exterior first, then garages, basements and crawl spaces. The debris is bagged rather than left to hatch.
- Time
- 30–90 minutes
- Best for
- Visible webbing on eaves, porches, sheds and basements
Monitoring and Follow-Up
$50–$150 per visit
Ask what the follow-up visit found. Tracking traps shows whether the plan works.
- Time
- 20–45 minutes
- Best for
- Confirming results; recluse or widow properties
Exterior Perimeter Treatment and Void Dusting
$150–$350
Once webs are down, a technician in Longmont applies a residual product along the foundation, around door and window frames, and under eaves. Spiders crossing those bands pick up the product.
- Time
- 45–120 minutes
- Best for
- Heavy exterior activity, widows or recluses confirmed
Prices are typical published ranges. Ask what’s included before you compare quotes.
Crawl spaces and their vents are worth a look with a flashlight, especially if a widow has turned up outside.Which spiders live around Longmont.
All are harmless to people. Around Longmont, they're western black widows, usually hiding under decks, grills and meter covers. Brown recluses don't live around Longmont. Most suspects turn out to be harmless look-alikes. Most spiders in Longmont homes are house spiders, cellar spiders, jumping spiders and wolf spiders.
Local spiders conditions in Longmont.
Across Longmont, the area is mostly suburban, so spiders 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 Longmont usually starts outside and works inward, checking the foundation, gaps around doors and windows, and any moisture or clutter near the structure first. 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. 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. Longmont sits in a semi-arid climate, and that sets the pace for spider activity here: late summer through fall (August-October).
Mesh and sealant around a pipe entry close off a gap spiders would otherwise use.When you’ll see more of them.
That's when males wander. Winter lows around 16°F in Longmont slow spiders outside, but house spiders carry on indoors. Spring brings a new hatch. Clear egg sacs in winter. You'll see the most in late summer and fall.
Where they hide in houses here.
Check window wells, storage areas and the sill plate. Clutter gives them endless hiding spots. Plenty of homes in Longmont have basements, and basements are spider central.
A year of spiders in Longmont.
- Winter: with lows near 16°F in Longmont, a good time to clear clutter and seal gaps. - Spring: new spiderlings hatch. Vacuum webs and egg sacs. - Summer: highs near 88°F in Longmont bring more insects, and more spiders. - Fall: males wander indoors. Peak spider season.
Harmless or worth a closer look?
- Orb weaver: big round web outside. Harmless. - Black widow: shiny black, red hourglass underneath. Leave it alone. - Brown recluse: tan, violin mark on its back, plain legs. - Wolf spider: big, hairy and fast. Harmless. - Cellar spider: tiny body, very long legs. Harmless. - Jumping spider: small, fuzzy, hops. Harmless.
If you think you’ve been bitten.
Use a cool compress. Raise the area if you can. See a doctor for severe pain, cramping or spreading redness. If you can, safely catch the spider for identification. Wash the bite with soap and water.
Fewer spiders, the easy way.
- Beds: keep them a few inches from the wall. - Lights: yellow bug lights draw fewer insects. - Gaps: add door sweeps and repair screens. - Clutter: store things in sealed plastic bins, not cardboard. - Webs: vacuum webs and egg sacs every few weeks. - Shoes and gloves: shake them out before use.
Webs outside: leave some, clear some.
- Gloves: wear them when moving firewood, pots or patio cushions. - Garden orb weavers: leave them. They catch flies and mosquitoes. - Doorways and porch lights: brush webs away weekly. - Eaves and window frames: a long-handled brush works well. - Woodpiles: keep them off the ground and away from the house.
Spider myths.
- Every blister is a recluse bite: most aren’t spider bites. - Swallowing spiders in your sleep: no evidence it happens. - Daddy longlegs are deadly: no. They’re harmless. - Spiders move in for winter: most house spiders never leave.
Spiders and pets.
A widow bite can sicken a dog or cat. your vet. Some sprays are risky for cats. Ask the company which products are cat-safe. Most spiders are no threat to pets.
What a spider visit looks like.
The tech walks the outside first. They knock down webs and egg sacs around eaves and windows. They treat cracks, gaps and hiding spots, not open lawn. Inside, they focus on corners, closets and the garage. Most visits take about an hour.
Sticky traps tell you a lot.
Check them after a week. They show which spiders you have and where they travel. Set sticky traps along baseboards, behind furniture and in the garage.
Outdoor lights and spiders.
Yellow bulbs attract fewer bugs. Motion-sensor lights help too. Porch lights draw insects, and insects draw spiders.
Cellar spiders in the basement.
They're harmless and even eat other spiders. A dehumidifier and a broom keep them in check. Long-legged cellar spiders hang in basement corners.
Spiders in the garage.
Store things in sealed bins off the floor. A door sweep and a sticky trap by the door help. Garages collect webs, boxes and insects.
Questions to ask before you sign.
- When can kids and pets go back in? - Which spiders did you find? - Where will you treat, inside and out? - Is web and egg-sac removal included? - Will you seal gaps or add door sweeps? - What happens if they come back?
What affects the price
- One-time visit versus recurring plan.
- Exterior siding type and number of gaps.
- Bundling with an existing general pest plan.
- Eave depth and roofline height.
- Whether a widow or recluse is confirmed.
- Door sweeps, screens and sealing work.
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What's your biggest concern about spiders?
When to call for help
Call if a black widow is near where kids play. if spiders keep coming back after cleaning. High eaves and attics are worth leaving to a pro.
What you can do yourself
A pro adds targeted treatment in cracks and voids. They don't reach hiding spots. Skip foggers. Add door sweeps and store things in sealed bins. Switch to yellow bug lights. Start simple.
Spiders in Longmont
Longmont only gets about 14 inches of rain a year, so spiders gather where insects find water: garages, sprinkler zones and shaded walls. In Longmont's neighborhoods, eaves, porch lights, woodpiles and garages are spider favorites. Longmont has a semi-arid climate, and spiders activity here tends to pick up late summer through fall (August-October). Across Longmont, most of the housing is suburban, so the usual entry points, moisture spots, and sheltered areas near the structure are what an inspection checks first. Across Longmont, 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 Longmont and Colorado can point out the specific conditions that matter most here before you commit to a plan.
Local research
Spiders in Longmont, CO: what the public record shows
Before you compare quotes, it helps to know which spiders 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.
Spider species recorded in Colorado
- Western black widow (Latrodectus hesperus) — 'The black widow spider, Latrodectus hesperus, is the most common harmful spider in California' and 'occur in most parts of California' (UC IPM); 'common in Colorado' (CSU); Lat…
- Funnel weavers (grass spiders) (Agelenidae) — 'The most common spiders found in homes, particularly during late summer and early fall' in Colorado (CSU).
When spiders are busiest around Longmont
'Funnel web spiders are the most common spiders found in homes, particularly during late summer and early fall'; 'Some spiders wander indoors in the early fall' (CSU).
'Widow spiders, particularly the western widow (Latrodectus hesperus), are common in Colorado' (CSU).
For context, nationally
- Throughout North America, but are most common in the southern and western United States — Black widow distribution. CDC/NIOSH
- In the midwestern and southern United States — Brown recluse distribution. CDC/NIOSH
Sources: Spiders in the Home (5.512); CDC/NIOSH; Pest Notes: Spiders (PN 7442). Figures are quoted as the source prints them. How we check our sources
Simple ways to keep spiders away
- Move fixtures away from doors where possible.
- Put exterior lights on motion sensors.
- Inspect items brought in from sheds and garages.
- Trim shrubs a foot back from siding.
- Repair torn window and vent screens.
- Switch porch bulbs to warm or yellow LEDs.
Under-sink cabinets get checked for gaps around pipes, which spiders and their prey both use.Did you know?
Some spiders can survive months without a meal
Male black widows are tiny, patterned and harmless
Questions people ask
Why are there suddenly so many spiders in fall?
Males wander in late summer and fall looking for mates. Many end up indoors by accident. It usually settles down in a few weeks.
Do spider sprays actually work?
Store-bought sprays kill what they touch. They rarely reach hiding spots. Removing webs and egg sacs and sealing gaps works better.
Are the spiders in my house dangerous?
Almost always no. Most house spiders can't hurt you. Widows and recluses are the main exceptions in the U.S.
Will treatment get rid of all the spiders?
No, and that's fine. The goal is fewer spiders indoors. A few outside help control other pests.
Should I use a fogger or bug bomb for spiders?
No. Foggers don't reach where spiders hide. They can also be a fire risk if used wrong.
What does a spider spray cost?
Between $200 and $500 is Local quotes vary; ask for a written estimate. As you collect quotes in Longmont, ask each company what's typical on your street.
Does every house have spiders?
Nearly, based on the best available room-by-room study. Across Longmont, one hundred percent of 50 North Carolina homes in a 2012 study held spiders, living or dead. A good pro in Longmont will explain how their plan fits what they found at your home.
Are there dangerous spiders in Longmont?
Black widows, yes, as almost everywhere. Most other spiders here are harmless.
When are spiders worst in Longmont?
Late summer and fall, when males wander.
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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 Spider Exterminator · Updated September 11, 2026 · How we write these guides