The short version
Most spiders in Denver are harmless. Black widows live here, as in every lower-48 state. Denver 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 Denver 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.
- 1Many tiny spiders in one spot after a hatch.
- 2Messy, funnel-shaped webs in shrubs and grass.
- 3Webs under deck boards and outdoor furniture.
- 4A pale spider in a silk pocket near the ceiling.
- 5Tan spider with a violin mark and six eyes.
- 6Small flying insects gathering under exterior lights.
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 inspection maps webs, entry cracks and what the spiders eat. Everything that follows is built on that map.
- Time
- 45–90 minutes
- Best for
- Every job; the species decides how much to do
Exterior Perimeter Treatment and Void Dusting
$150–$350
Sprays alone do a mediocre job on spiders, which is why Denver pros pair them with dusting. A light dust goes into weep holes, voids and behind fixtures.
- Time
- 45–120 minutes
- Best for
- Heavy exterior activity, widows or recluses confirmed
Web and Egg-Sac Removal
$100–$250
Around Denver, 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 for a note of what the follow-up turned up. Tracking traps shows whether the plan works.
- Time
- 20–45 minutes
- Best for
- Confirming results; recluse or widow properties
Prices are typical published ranges. Ask what’s included before you compare quotes.
Lidded plastic bins beat open boxes and loose piles for keeping spiders out of stored clothes and bedding.Which spiders live around Denver.
Most suspects turn out to be harmless look-alikes. Brown recluses don't live around Denver. Around Denver, they're western black widows, usually hiding under decks, grills and meter covers. All are harmless to people. Most spiders in Denver homes are house spiders, cellar spiders, jumping spiders and wolf spiders.
Local spiders conditions in Denver.
A provider who works Denver 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 Denver'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 Denver usually starts outside and works inward, checking the foundation, gaps around doors and windows, and any moisture or clutter near the structure first. Around Denver, the area is mostly urban, 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. Denver 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.
Clear egg sacs in winter. Spring brings a new hatch. Winter lows around 19°F in Denver slow spiders outside, but house spiders carry on indoors. That's when males wander. You'll see the most in late summer and fall.
Where they hide in houses here.
Clutter gives them endless hiding spots. Check window wells, storage areas and the sill plate. Plenty of homes in Denver have basements, and basements are spider central.
A year of spiders in Denver.
- Winter: with lows near 19°F in Denver, a good time to clear clutter and seal gaps. - Fall: males wander indoors. Peak spider season. - Summer: highs near 88°F in Denver bring more insects, and more spiders. - Spring: new spiderlings hatch. Vacuum webs and egg sacs.
Harmless or worth a closer look?
- Orb weaver: big round web outside. Harmless. - Jumping spider: small, fuzzy, hops. Harmless. - Cellar spider: tiny body, very long legs. Harmless. - Wolf spider: big, hairy and fast. Harmless. - Brown recluse: tan, violin mark on its back, plain legs. - Black widow: shiny black, red hourglass underneath. Leave it alone.
If you think you’ve been bitten.
If you can, safely catch the spider for identification. See a doctor for severe pain, cramping or spreading redness. Raise the area if you can. Use a cool compress. Wash the bite with soap and water.
Fewer spiders, the easy way.
- Beds: keep them a few inches from the wall. - Shoes and gloves: shake them out before use. - Webs: vacuum webs and egg sacs every few weeks. - Clutter: store things in sealed plastic bins, not cardboard. - Gaps: add door sweeps and repair screens. - Lights: yellow bug lights draw fewer insects.
Webs outside: leave some, clear some.
- Gloves: wear them when moving firewood, pots or patio cushions. - Woodpiles: keep them off the ground and away from the house. - Eaves and window frames: a long-handled brush works well. - Doorways and porch lights: brush webs away weekly. - Garden orb weavers: leave them. They catch flies and mosquitoes.
Spider myths.
- Every blister is a recluse bite: most aren’t spider bites. - Spiders move in for winter: most house spiders never leave. - Daddy longlegs are deadly: no. They’re harmless. - Swallowing spiders in your sleep: no evidence it happens.
Spiders and pets.
Ask the company which products are cat-safe. Some sprays are risky for cats. your vet. A widow bite can sicken a dog or cat. Most spiders are no threat to pets.
What a spider visit looks like.
Inside, they focus on corners, closets and the garage. They treat cracks, gaps and hiding spots, not open lawn. They knock down webs and egg sacs around eaves and windows. The tech walks the outside first. Most visits take about an hour.
Sticky traps tell you a lot.
They show which spiders you have and where they travel. Check them after a week. Set sticky traps along baseboards, behind furniture and in the garage.
Outdoor lights and spiders.
Motion-sensor lights help too. Yellow bulbs attract fewer bugs. Porch lights draw insects, and insects draw spiders.
Cellar spiders in the basement.
A dehumidifier and a broom keep them in check. They're harmless and even eat other spiders. Long-legged cellar spiders hang in basement corners.
Spiders in the garage.
A door sweep and a sticky trap by the door help. Store things in sealed bins off the floor. Garages collect webs, boxes and insects.
Questions to ask before you sign.
- When can kids and pets go back in? - What happens if they come back? - Will you seal gaps or add door sweeps? - Is web and egg-sac removal included? - Where will you treat, inside and out? - Which spiders did you find?
What affects the price
- Whether a widow or recluse is confirmed.
- Amount of clutter in garage, basement and storage.
- Season and how heavy current activity is.
- Wooded, wet or open-field surroundings.
- Bundling with an existing general pest plan.
- Whether outbuildings, sheds and decks are included.
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Which spider concerns you most in your Denver home?
When to call for help
High eaves and attics are worth leaving to a pro. if spiders keep coming back after cleaning. Call if a black widow is near where kids play.
What you can do yourself
Start simple. Switch to yellow bug lights. Add door sweeps and store things in sealed bins. Skip foggers. They don't reach hiding spots. A pro adds targeted treatment in cracks and voids.
Spiders in Denver
Denver only gets about 14 inches of rain a year, so spiders gather where insects find water: garages, sprinkler zones and shaded walls. In denser parts of Denver, spiders favor stairwells, garages, basements and window frames. Denver has a semi-arid climate, and spiders activity here tends to pick up late summer through fall (August-October). Around Denver, 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 Denver, 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 Denver and Colorado can point out the specific conditions that matter most here before you commit to a plan.
Local research
Spiders in Denver, 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 Denver, 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 Denver
'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
- Vacuum webs and egg sacs weekly during warm months.
- Move fixtures away from doors where possible.
- Close windows at night or use tight screens.
- Keep beds a few inches from the wall.
- Seal gaps around pipes, cables and vents.
- Reduce clutter in closets and storage rooms.
Under-sink cabinets get checked for gaps around pipes, which spiders and their prey both use.Did you know?
Spiderlings travel miles by ballooning on silk threads
Jumping spiders see in color and plan their route before they pounce
Questions people ask
Do brown recluses live in my area?
Probably not. Colorado is outside the brown recluse range.
What attracts spiders to a house?
Food, mostly. Spiders follow insects to porch lights, damp spots and clutter. Cut the insects and spiders follow.
How do I choose a spider control company?
Check that they're licensed in Colorado. Ask them to identify the spiders before treating. Ask what's included and what happens if they come back.
Why do spiders keep coming back after I clean?
Usually because the insects they eat are still around. Egg sacs and gaps around doors also keep them coming.
Can I just leave the spiders alone?
Most house spiders are harmless and eat other pests. Widows are the exception, so check under outdoor furniture.
What does a severe spider infestation cost to treat?
Around Denver, between $300 and $1,000 is Local quotes vary; ask for a written estimate. A good pro in Denver can explain why their plan matches what they found at your place.
How much does spider extermination cost?
Around Denver, between $100 and $300 is Local quotes vary; ask for a written estimate. Ask each company quoting in Denver what they usually find in your part of town.
Are there dangerous spiders in Denver?
Black widows, yes, as almost everywhere. Most other spiders here are harmless.
When are spiders worst in Denver?
Late summer and fall, when males wander.
Nearby cities
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Sources (12)
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