Spiders get into your house through surprisingly small gaps in your home’s exterior, and they’re usually following the food. Every crack around a window frame, every gap beneath a door, and every unsealed utility opening is a potential entrance. Understanding exactly where they’re coming in and what’s drawing them there is the first step to seeing fewer of them indoors.
The Most Common Entry Points
Spiders don’t need much space. A gap of just a millimeter or two is enough for most household species to squeeze through. The five most common entry points are window gaps, door frames, foundation cracks, vents, and utility openings where pipes or wires pass through exterior walls.
Foundation cracks are especially productive entry points because they sit at ground level, right where many spider species live and hunt. Even hairline cracks in a concrete foundation can widen over time with seasonal expansion and contraction. Door frames are another major one: if you can see daylight beneath your front door or around the edges of the frame, spiders can get through. The same goes for garage doors, which often have worn or missing seals along the bottom edge.
Utility openings are easy to overlook. Anywhere a cable line, gas pipe, dryer vent, or water line enters your house, there’s usually a gap around it. These penetrations are often sealed loosely with caulk that cracks and separates over time. Dryer vents and bathroom exhaust vents that lack tight-fitting covers are essentially open doors.
You Might Be Carrying Them Inside
Not every spider walks in on its own. Firewood is one of the most common vehicles. Several species of spiders overwinter under bark and in the soft tissue of dead wood, and when you bring that wood into a warm house, they wake up and start moving around. Stripping bark from logs before carrying them inside eliminates some hitchhikers, and splitting the wood open can expose insects and spiders hiding in the interior.
Cardboard boxes are another frequent transport method, especially boxes that have been stored in a garage, shed, or storage unit. Spiders and their egg sacs tuck into the folds and flaps of corrugated cardboard. Potted plants brought indoors for winter, grocery bags, and even holiday decorations pulled out of attic storage can all carry spiders or egg sacs into your living space. One egg sac can contain dozens to hundreds of spiderlings depending on the species, so a single hitchhiker can turn into a noticeable indoor population.
What’s Attracting Them to Your House
Spiders are predators, and they go where the food is. The biggest attractant isn’t anything about your house specifically. It’s the insects your house draws in. Outdoor lighting is a major factor: porch lights, security lights, and illuminated house numbers all pull flying insects to your exterior walls and doorways. Spiders aren’t interested in the light itself, but they build webs near those lights because that’s where their prey gathers. You’ll often notice webs accumulating around entry doors, exterior walls near lights, and any brightly lit area of your home’s exterior.
Moisture is another draw. Leaky outdoor faucets, clogged gutters, and poor drainage near the foundation create damp conditions that attract both insects and the spiders that eat them. Cellar spiders, one of the most common indoor species, specifically seek out dark, humid spaces like basements, crawl spaces, and garages. If your basement or crawl space has moisture issues, you’re creating ideal habitat.
Clutter matters too. Stacks of boxes, piles of clothes on the floor, undisturbed storage areas, and dense landscaping right against your foundation all provide shelter. Spiders prefer quiet, undisturbed spots where they can build webs or hunt without being bothered.
Why Fall Is the Worst Season
If you’ve noticed more spiders lately and it’s August through October, that’s not a coincidence. Funnel web spiders are the most common spiders found in homes, and they’re especially prevalent during late summer and early fall. Yellow sac spiders are the most common species found wandering through homes during fall, particularly at night. Some ground spider species also move indoors when temperatures drop.
Wolf spiders occasionally enter homes too, particularly in areas of new construction or development where their outdoor habitat has been disturbed. These are the large, fast-moving spiders that tend to alarm people the most, and they don’t build webs. They’re active hunters that wander in through ground-level openings.
The seasonal spike happens for two reasons: mature spiders are on the move looking for mates, and cooling temperatures push insects (and the spiders hunting them) toward the warmth radiating from your home’s exterior.
How to Seal Them Out
Physical exclusion is the most effective long-term strategy. Start with a walk around your home’s exterior, looking for every gap, crack, and opening.
- Door sweeps: Install sweeps on every exterior door, including the garage. Look for products that seal gaps up to an inch, ideally ones with a combined rubber and mesh design that blocks both rodents and insects. If you can slide a credit card under your door, spiders can get through.
- Weatherstripping: Replace worn or compressed weatherstripping around doors and windows. Check both the sides and top of the frame, not just the bottom.
- Foundation cracks: Seal cracks with exterior-grade silicone caulk or hydraulic cement for larger gaps. Pay special attention to where the foundation meets the siding.
- Utility penetrations: Caulk or foam around every pipe, wire, and cable that passes through an exterior wall. Check both inside and outside.
- Window screens: Repair or replace any screens with holes or tears. Make sure screens fit tightly in the frame with no gaps at the edges.
- Vents: Install fine mesh covers over dryer vents, soffit vents, and crawl space vents. Standard hardware cloth works, but finer mesh blocks smaller insects that attract spiders.
Reducing What Draws Them In
Sealing entry points works best when you also reduce the reasons spiders want to be near your house in the first place. Switch outdoor lighting to yellow or warm-toned LED bulbs, which attract fewer flying insects than standard white lights. If possible, move lights away from doors and windows, or use fixtures that direct light downward rather than outward. When you reduce the insects gathering at your exterior lights, you remove the food source that brings spiders to your walls and doorways.
Pull mulch, leaf litter, and dense vegetation back from your foundation by at least a foot. Stacked firewood should be stored well away from the house and elevated off the ground. Fix any moisture problems: repair leaky spigots, clean gutters, and make sure the ground slopes away from your foundation so water doesn’t pool.
Inside, reduce hiding spots. Clear floor clutter, move storage boxes off the floor onto shelves, and swap cardboard boxes for plastic bins with tight lids. Vacuum regularly along baseboards, in corners, and behind furniture. Vacuuming removes both spiders and their webs, and it destroys egg sacs before they hatch.
Do Natural Repellents Actually Work?
Peppermint oil is the most popular DIY spider repellent online, but the science is mixed. A study published in the Journal of Economic Entomology tested three commonly recommended natural repellents: peppermint oil, lemon oil, and chestnuts. Researchers at the University of Ulm and the University of Toronto tested them against three spider species using a Y-shaped tube where spiders could choose to move toward or away from the substance.
Peppermint oil and chestnuts did show repellent effects on two of the three species tested, with those spiders avoiding the substances in more than 75 percent of trials. But the third species was completely unaffected. Lemon oil, despite being the most frequently recommended repellent in online search results, had no significant effect on any of the three species.
The takeaway: peppermint oil might discourage some spiders in some situations, but it’s not a reliable barrier. It won’t replace sealing gaps and reducing attractants. If you want to try it, a few drops of peppermint essential oil diluted in water and sprayed around entry points is harmless enough, but don’t expect it to solve the problem on its own.