Black house spiders are persistent but manageable. Getting rid of them takes a combination of removing their webs, sealing the gaps they use to get inside, and reducing the insects they feed on. A single approach rarely works on its own, but layering a few methods together can clear an infestation within weeks and keep spiders from returning.
Identify What You’re Dealing With
Black house spiders (Badumna insignis) are dark, sturdy spiders with brown-to-black legs and a charcoal grey abdomen that sometimes has pale markings. Females run about 12 to 18 mm long, males slightly smaller at 9 to 15 mm. Their signature tell is their web: a messy, lacy sheet with one or more funnel-shaped retreats leading into a crack or crevice. You’ll most often find these webs around window frames, door frames, brickwork, eaves, fences, and wall gaps. They’re sometimes called “window spiders” for exactly this reason.
If you’re seeing tidy orb webs or wispy cobwebs in ceiling corners, you likely have a different species. Correctly identifying the spider matters because it determines how aggressive your approach needs to be and where to focus your efforts.
Remove Existing Webs and Spiders
Start with direct removal. A vacuum with a hose attachment is the fastest way to clear webs and capture spiders without getting close. Hit every window frame, door frame, eave, and exterior corner where you see lacy webbing. Black house spiders are strongly attached to their webs and will often be sitting in the funnel retreat, so vacuuming the web usually takes the spider with it. Dispose of the vacuum bag or empty the canister outside immediately.
For outdoor areas you can’t easily vacuum, a long-handled broom or a specialized cobweb brush (sometimes called a “webster”) works well. Removing the webs forces spiders to expend energy rebuilding, and repeated removal over a few weeks discourages them from reestablishing in the same spot. This is especially important because black house spiders tend to build on top of old webbing, so leaving remnants invites them back.
Seal Entry Points
Spiders follow insects indoors, and both get in through surprisingly small gaps. A crack as narrow as 1/16 of an inch is enough. A thorough sealing job is the single most effective long-term fix. Focus on these areas:
- Door thresholds. Install door sweeps on all exterior doors. Lie on the floor and check for light filtering underneath. Caulk along the bottom outside edge and sides of each threshold. Garage doors should have a rubber bottom seal (vinyl cracks in cold weather).
- Windows. Caulk any gaps around window frames using silicone or acrylic latex caulk. Repair torn or loose window screens.
- Utility openings. Seal gaps where pipes, wires, outdoor faucets, dryer vents, and cable lines enter the foundation or siding. These are common spider entry points. Use caulk, expandable foam, steel wool, or copper mesh depending on the size of the gap.
- Sliding glass doors. Line the bottom track with half-inch to three-quarter-inch foam weatherstripping.
- Vents. Cover attic, roof, and crawl space vents with quarter-inch wire mesh (hardware cloth).
This is labor-intensive, but it solves the problem at the source. Every gap you close reduces both spiders and the insects that draw them in.
Cut Off Their Food Supply
Black house spiders eat insects, and they build webs wherever insects are abundant. Reducing insect activity around your home makes the location less attractive. Switch exterior lights to yellow or warm-toned LED bulbs, which attract fewer flying insects than standard white lights. Move bright lights away from doorways and windows when possible, or use fixtures that direct light downward rather than outward.
Keep outdoor areas tidy. Clear woodpiles, leaf litter, and dense vegetation away from the house walls. These provide shelter for both insects and spiders. Inside, store items off the floor in sealed bins rather than cardboard boxes, especially in garages, basements, and storage rooms.
Use Sticky Traps for Monitoring and Capture
Sticky traps (glue boards) placed along walls are useful for catching spiders and showing you where activity is concentrated. Place them flat against the wall with the open ends running parallel to it, since spiders and insects naturally travel along edges in dark areas. Space them 5 to 10 feet apart in rooms where you’ve noticed spiders, particularly along garage walls, in storage areas, and behind furniture.
Sticky traps work better as a monitoring tool than as a standalone solution. They won’t eliminate an infestation by themselves, but they’ll tell you whether your other efforts are working and help you pinpoint problem areas you might have missed.
Chemical Barrier Treatments
If sealing and cleaning aren’t enough, an insecticide barrier spray around the home’s perimeter can fill the gaps. Products containing synthetic pyrethroids (look for active ingredients like bifenthrin, cyfluthrin, deltamethrin, or lambda cyhalothrin on the label) are effective against spiders. Apply them as a barrier at the base of all exterior doors, around garage and crawl space entrances, foundation vents, utility openings, and underneath the lowest edge of siding. Treating a 2- to 6-foot band along the ground around the foundation and 2 to 3 feet up the foundation wall creates a perimeter that spiders must cross.
These treatments typically need to be reapplied monthly or every other month during warmer seasons when spiders are most active. Always follow the product label for application rates and safety precautions, and keep pets and children away from treated surfaces until they’ve dried.
Do Natural Repellents Work?
Peppermint oil is the most commonly recommended natural spider repellent, and there is some evidence behind it. A 2018 study found that peppermint oil strongly repelled two out of three spider species tested. Lemon oil, despite being widely marketed as a spider deterrent, showed no repellent effect in the same study.
To try peppermint oil, mix 10 to 15 drops per ounce of water in a spray bottle. Adding a dispersing agent (like solubol, available online) helps since essential oils don’t dissolve well in water on their own. Shake thoroughly and spray around window frames, door frames, and other spots where you’ve seen webs. Reapply every week or two, as the scent fades quickly. This approach is best used as a supplement to physical exclusion and cleaning, not a replacement. It may discourage spiders from building in treated spots, but it won’t eliminate an established population.
When to Call a Professional
If you’ve sealed entry points, cleared webs repeatedly, and applied barrier treatments but still see heavy spider activity after several weeks, professional pest control is a reasonable next step. Expect to pay between $150 and $300 for a targeted spider treatment. Professionals typically remove existing activity with specialized tools, then apply exterior perimeter treatments to prevent re-entry. Many companies also offer quarterly or annual maintenance plans that include spider coverage.
Professional help is particularly worth considering if you’re unsure what species you’re dealing with. Black house spiders are not considered dangerous to healthy adults. The vast majority of bites cause only minor local reactions like pain, redness, and swelling. Extremely rare cases have been linked to skin ulceration, but the Australian Venom Research Unit notes that evidence for this is limited and poorly understood. That said, if you suspect you’re seeing black widows or brown recluses (which look quite different from black house spiders), professional identification and treatment become more important.
What to Do if You’re Bitten
A black house spider bite is typically a minor event. Clean the bite with mild soap and water, apply a cool cloth for 15 minutes each hour to reduce swelling, and take an over-the-counter pain reliever if needed. An antihistamine or calamine lotion can help with itching. If the area around the bite grows significantly larger, develops spreading red streaks, or you experience trouble breathing or severe pain, seek medical attention promptly.