How to Keep Spiders Out of Your House — What Actually Works (2026)

Why Do Spiders Come Inside in Late August? (It’s Not the Cold)

Every year, right on schedule, the last week of August turns quiet houses into spider theatres — one crossing the living-room floor at 10 p.m., another in the bathtub by morning. The near-universal explanation is that spiders are “coming in to escape the cold.” It is a tidy story, and it is wrong.

What actually happens is mating season. From late August through October, mature male house spiders reach adulthood, abandon their webs and hiding spots, and start wandering in search of females. A male on a mission covers a lot of floor, and floors are where you notice him. Crucially, most of these spiders did not just arrive from the garden — arachnologists who have studied indoor spider populations consistently find that the species you meet in fall are house spiders that have been living in your basement, wall voids, closets, and window frames all along. The population did not spike; its visibility did.

This reframing matters for two practical reasons. First, it tells you the fall surge is self-limiting — the wandering males mate and die, and by November the theatre closes on its own. Second, it tells you where to aim your effort: if the spiders are already resident, then squishing the ones you see is trimming leaves, while sealing entry points and cutting off their food supply is pulling roots. That is the plan this guide lays out.

First, the Reassuring Part: House Spiders Are Effectively Harmless

Before spending a dollar on control, calibrate the threat, because it is smaller than nearly anyone believes. There are no medically significant spiders established in most of Canada. The cast you actually meet indoors — cellar spiders (the spindly “daddy long-legs” type), common house spiders, the occasional wolf spider that hitchhiked in, and charismatic little jumping spiders — either cannot pierce human skin at all or can manage, at absolute worst, something like a mild bee sting. Genuinely dangerous encounters are so rare that Canadian emergency medicine treats “spider bite” diagnoses with heavy skepticism; most turn out to be infected scratches or other insect bites.

The two famous villains deserve a sentence each. Black widows exist in Canada only in small pockets of the southern edge of the country, are extremely shy, and live in undisturbed outdoor clutter — woodpiles, sheds, rarely a living room. Brown recluses are not established in Canada at all, decades of misattributed “recluse bites” notwithstanding. If you are reading this from the southern United States, both species are real where you live, but the same behavioural truth applies: they are reclusive by nature and are found in undisturbed storage and clutter, not patrolling your ceiling.

None of this means you have to enjoy sharing a bathroom with spiders. It means the goal is comfort, not safety — which frees you to pick calm, effective methods instead of reaching for the most aggressive spray on the shelf.

What Works vs What Doesn’t: The Evidence Table

Spider prevention is drowning in folk remedies, so here is the field sorted by evidence. Note the pattern: the physical methods carry the weight, the chemical barrier is a legitimate supplement, and the popular “natural” options bring up the rear.

As an Amazon Associate, BuzzSkito earns from qualifying purchases. BuzzSkito only points to products we would genuinely use or recommend, at no extra cost to you.

Check current availability of the three tools that do the heavy lifting:

Step 1: Seal the Entry Points (The Only Permanent Fix)

Spiders do not chew, drill, or force anything — every spider in your house walked in through an opening that already existed, or hatched from an egg sac that rode in on something. Close the openings and you have solved the problem at the architectural level, permanently, with zero ongoing cost. Work through the list in order of impact:

• The gap under exterior doors. This is the superhighway. If you can see daylight under a door, spiders, and the insects they follow, treat it as an open invitation. An exterior-grade door sweep installs in under an hour with a screwdriver and closes the single biggest entry route in the house.
• Perished weatherstripping. Compressed, cracked foam around door and window frames leaves corner gaps that are spider-sized by definition. Replacing it is cheap, and the payoff is double: fewer arthropods and lower heating bills.
• Window screens. A torn or gapped screen turns every summer evening of open windows into an arthropod open house. Patch small tears with adhesive screen patches; re-mesh anything worse. Check that screens seat snugly in their frames — a bowed frame leaves an entry slot along the edge.
• Utility penetrations. Where cable, gas, AC lines, and dryer vents pass through the wall, the hole is nearly always bigger than the pipe. Stuff larger gaps with copper mesh or backer rod, then seal with exterior caulk. Cover vent openings with fine insect mesh where the vent design allows it.
• Foundation cracks and basement windows. Walk the foundation with a caulk gun on a dry day. Basement window wells are classic spider real estate — clear the leaf litter that accumulates in them and screen the wells if spiders are a recurring theme.

One honest caveat: sealing keeps new spiders out; it does nothing about the residents already inside. That is what the next two steps are for — and it is why the glue traps matter, because they will tell you whether your interior sightings are fading as the resident population winds down.

Step 2: Vacuum, Don’t Squish

For the spiders already indoors, the vacuum cleaner is the best control device you own, and it beats the rolled-up magazine on every axis:

• It removes egg sacs. This is the big one. A single common house spider egg sac — the small silk ball tucked into a web corner — can hold 100–400 eggs. Squish the spider and leave the sac, and you have accomplished close to nothing. A vacuum pass along cobwebbed corners, behind furniture, around basement ceiling joists, and inside closet corners removes spiders, webs, and the next generation in one motion.
• It avoids the wolf-spider surprise. Female wolf spiders carry their spiderlings on their abdomen. Crush one with young aboard and the survivors scatter — dozens of them, in every direction. The vacuum avoids the memory entirely.
• It doubles as prevention. Regular vacuuming of the corners, baseboards, and undisturbed zones spiders prefer removes not just spiders but the web anchor points and the debris that shelters their prey.

Empty the canister or bag into an outdoor bin. And if the spider is large, magnificent, and you would rather it lived — this is what the long-handled spider catcher in our picks is for. Catch it at arm’s length, walk it outside, release. Children find the demonstration formative; the spider is indifferent but alive.

Step 3: Sticky Traps — Your Monitoring System

Flat glue boards are the most underrated tool in spider management, and the reason is that people misunderstand the job. They are not primarily a kill device — they are intelligence. Placed flush against baseboards, behind the couch, along the garage wall, under the basement stairs, and behind the toilet, they intercept exactly the population you actually see: ground-travelling wanderers, which in fall means the roaming males.

Read them like instruments. The trap in the furnace room that fills while the bedroom trap stays empty just told you where the activity is. Traps that catch heavily in week one and taper to nothing by week four are documenting your success. And the bycatch is diagnostic too: a trap full of sowbugs and springtails is a moisture report on your basement, and a trap full of prey insects explains precisely why spiders find your house hospitable — which brings us to the food supply.

Expectations, honestly stated: web-building females rarely leave their webs, so glue boards will not eliminate an established population alone. They intercept, they inform, and they cost little enough to deploy a dozen. Pair them with sealing and vacuuming, and they close the loop on whether the plan is working.

Step 4 (Optional): A PMRA-Registered Perimeter Spray — and the Grey-Market Trap

If you want a chemical backstop, the right tool is a residual insecticide applied as a perimeter and crack-and-crevice treatment: along exterior door frames, foundation gaps, basement window wells, and the garage-to-house threshold. A residual product leaves a treated zone that keeps killing spiders (and their prey) that cross it for several weeks — a legitimate supplement to sealing, though never a substitute for it, since spray barriers fade and caulk does not.

Here is where Canadian buyers need to slow down, because the internet’s spider-spray advice is written almost entirely for Americans. In Canada, domestic pesticides must be registered with Health Canada’s PMRA and carry a registration number on the label. The widely stocked, Canadian-registered options for this job are Doktor Doom residual sprays and Konk OnGuard — both formulated and labelled for exactly this kind of perimeter and crack-and-crevice use in and around homes. That label is not bureaucratic decoration: it is the tested guidance on where the product may be applied, in what amounts, and with what re-entry precautions.

The product American blogs will push at you — Miss Muffet’s Revenge, a long-standing US spider-spray staple — is not PMRA-registered for sale in Canada. The same applies to various US-market Terro and Ortho spider formulations that differ from their Canadian counterparts. Importing unregistered pesticides is not a clever workaround; it is buying a product whose Canadian legal status, labelling, and formulation review simply do not exist. With registered alternatives on the shelf at Canadian retailers, there is no reason to go grey-market. Whatever you buy, read the label twice and follow it exactly — including keeping treated surfaces away from children and pets until dry.

The Peppermint Oil Question, Answered Honestly

Peppermint oil is the internet’s favourite spider remedy, so it deserves a straight answer rather than a wink. The best evidence in its favour is a small 2018 study in the Journal of Economic Entomology that found peppermint essential oil repelled spiders in a laboratory arena — a real result, worth taking seriously, and also worth reading closely: it worked on some species and not others, at close range, in a controlled chamber, while the volatile scent was fresh. Translating that to a real house means re-spraying windowsills every day or two, forever, to maybe deter a fraction of the species you host. No field study has ever demonstrated that peppermint oil keeps spiders out of an actual home.

Our verdict: if you like the smell, a peppermint spray along windowsills and door frames is a pleasant ritual with a possible marginal bonus, and it is completely harmless. Just be clear-eyed that you are buying air freshener with a hypothesis attached, and that a door sweep — a comparable one-time spend — will still be working in five years without a single re-application. The same folk-remedy shelf holds conkers, citrus peel, and cedar blocks, all of which have failed the tests they have been given, and plug-in ultrasonic repellers, which have failed every test across every pest they have been pointed at.

A Word in Defence of the House Centipede

While you are patrolling the basement, you may meet the house centipede — fast, fringed with improbable legs, and responsible for more shrieks per sighting than any spider. Here is the case for letting it be: the house centipede is one of the most effective predators your home can host. It actively hunts spiders, silverfish, carpet beetle larvae, cockroach nymphs, and fly larvae, it is essentially harmless to people, it builds no webs and damages nothing, and it will never multiply beyond what the food supply supports. In a guide about reducing spiders, it is literally on your side.

Its real value is as a messenger. A house with many centipedes is a house with plenty of prey — and usually a moisture source keeping that prey happy. Fix the damp (a dehumidifier in the basement, a fixed leak, cleared window wells) and both the prey and the predators taper off on their own. That is the pattern worth internalizing, and it is the last piece of the plan.

The Root Cause: Spiders Follow Food

Everything above manages spiders directly. The deepest fix manages their economy. Spiders settle where hunting is good — a house with abundant flies, gnats, moths, and other small insects will recruit and retain spiders no matter how many you remove, because the vacancy keeps getting re-advertised. Cut the prey base and the spider population follows it down without another intervention:

• Exterior lighting. White outdoor lights are insect magnets, and spiders famously build where the buffet lands. Swap entry lights for warm-toned or yellow “bug” LEDs and you will notice fewer webs around the porch within weeks.
• Indoor fliers. A kitchen with a fruit fly problem is a spider feeding station. Our guides on getting rid of fruit flies and the best fruit fly traps shut that supply line down; for general small fliers, an indoor UV trap like the one in our Katchy review quietly reduces the prey base in a problem room.
• Clutter and storage. Cardboard boxes on basement floors are spider condominiums — dark, undisturbed, corrugated hunting grounds. Move long-term storage into sealed plastic totes on shelving, and you remove both the habitat and the prey shelter in one upgrade.
• Moisture. Damp basements feed the springtails, sowbugs, and silverfish at the bottom of the food chain. A dehumidifier is, indirectly, spider control.

Put together, the whole plan fits in a weekend: seal the routes, vacuum the residents and their egg sacs, lay glue traps to watch the trend line, optionally lay down a PMRA-registered perimeter treatment, and starve the food chain. Do that in early August and the annual late-summer spider theatre plays to an empty house. If, despite diligent work, you face a genuinely heavy recurring infestation — or a confirmed black widow population in a southern region — that is the point where a licensed local pest professional earns their fee; our pest control cost guide covers what that typically runs.

Frequently Asked Questions

Related Household Pest Guides

• How to Get Rid of Fruit Flies — Full Playbook
• Best Fruit Fly Trap Canada — Tested Picks
• Katchy Indoor Insect Trap — Honest Canadian Review
• How to Get Rid of Wasps — Canadian Guide
• Raccoon Deterrents That Actually Work in Canada
• Pest Control Cost in Canada — What Pros Charge