Grass spiders are harmless, but their dense funnel-shaped webs can take over a lawn fast. The most effective approach combines regular web removal, yard maintenance to eliminate hiding spots, and sealing your home before fall, when these spiders start moving indoors. Here’s how to handle each part.
Know What You’re Dealing With
Grass spiders (genus Agelenopsis) are brownish or grayish, about a third to two-thirds of an inch long, with hairy legs that have dark banding. Their most distinctive feature is a pair of long, tail-like spinnerets extending from their rear end, which you can see with the naked eye. They build flat, sheet-like webs with a funnel retreat in one corner, typically in grass, shrubs, and ground cover.
These spiders are sometimes confused with brown recluses, but they’re easy to tell apart. Grass spiders have visible patterning on their abdomen, banded legs, and noticeably hairy bodies. Brown recluses are smooth, unmarked on the legs, and have only six eyes instead of eight. If you’re seeing funnel webs in your lawn, you almost certainly have grass spiders, not anything dangerous.
Timing Matters: When Grass Spiders Are Most Active
Grass spider eggs hatch in spring, and the young spiders grow through summer, reaching adult size by late summer. Web activity peaks from midsummer through early fall. This is when your lawn looks like it’s been draped in silk, especially on dewy mornings when the webs catch moisture and become visible.
The critical window for home invasion is autumn. As temperatures drop, grass spiders seek shelter indoors. The adults don’t actually survive the winter, so the indoor migration is short-lived, but it’s the period when most people notice spiders inside. Taking action in late summer, before this migration starts, gives you the best results.
Clear Webs From Your Yard
Funnel webs are easy to remove. A broom works for webs in shrubs and along foundations, and a garden hose on a strong setting washes webs out of grass and ground cover. Neither method kills the spider, which will typically flee and rebuild, but consistent removal discourages them from staying in that spot. If you’re removing webs every few days for a couple of weeks, most spiders will relocate.
For heavier infestations, mowing the lawn does double duty. It destroys webs and removes the tall grass that spiders prefer for web anchoring. A weekly mow during peak season keeps web density low.
Make Your Yard Less Inviting
Grass spiders set up where they can build undisturbed webs near ground level. That means tall grass, overgrown hedges, brush piles, leaf litter, and stacked debris are all prime real estate. A few changes to your yard make a noticeable difference:
- Mow regularly and keep grass at a consistent, moderate height. Letting it grow tall between mows creates exactly the sheltered conditions grass spiders love.
- Trim shrubs and hedges so the lower branches don’t rest on or near the ground. This removes the shaded, protected spaces where webs accumulate.
- Move firewood away from the house. Stacking wood directly against exterior walls attracts spiders looking for shelter and gives them a bridge straight to your siding.
- Clear brush piles, leaf litter, and yard waste promptly. These provide both habitat for spiders and food for the insects they eat.
- Don’t let outdoor trash accumulate. Food waste attracts insects, which in turn attract the spiders that feed on them.
Natural Deterrents That Help
Two options work without chemical pesticides. Diatomaceous earth (the food-grade kind, not pool-grade) is a fine powder made from fossilized organisms that damages the waxy coating on spiders and insects, dehydrating them. Sprinkle it dry around areas where you see heavy web activity, along foundation edges, and near entry points. It’s low risk for people and pets when used as directed, but you’ll need to reapply after rain since moisture renders it ineffective.
Essential oils containing mint or chestnut extract act as repellents rather than killers. Mixing a few drops with water in a spray bottle and applying it around doorways, windowsills, and web-prone areas can discourage spiders from settling in. These won’t eliminate a large population, but they’re a reasonable first step if you prefer to avoid anything stronger.
Keep Them Out of Your Home
Sealing entry points is the single most effective indoor prevention step. Grass spiders enter through gaps under doors, cracks in foundations, torn window screens, and spaces around utility pipes. Caulk or weatherstripping covers most of these. Pay special attention to ground-level openings, since grass spiders are ground-dwelling and tend to enter low rather than high.
Inside, glue traps placed along walls and in corners help you monitor whether spiders are getting in and where they’re traveling. These flat, sticky traps catch spiders passively and show you which entry points need better sealing. Place them along baseboards in basements, garages, and ground-floor rooms where spiders are most likely to appear.
If you find a grass spider indoors, the simplest removal is a glass and a piece of paper. Cover the spider, slide the paper underneath, and carry it outside. They’re fast runners but not aggressive, and their bite is essentially harmless to humans.
When to Use Insecticides
For large populations or situations where spiders are already migrating indoors in fall, chemical barriers can help. Granular insecticide products spread around your home’s foundation create a treated perimeter in the soil and mulch beds that spiders cross to reach your walls. Liquid residual sprays applied to baseboards, corners, and entry points work indoors. Aerosol sprays let you spot-treat individual webs and cracks without mixing concentrates.
Products containing bifenthrin, cyfluthrin, or deltamethrin are commonly used for spider control. Apply them in late summer before the fall migration begins for the best results. Keep children and pets away from treated surfaces until they’re fully dry, and ventilate indoor spaces well after spraying. Always follow the product label, since application rates and safety precautions vary.
For most yards, though, chemical treatment is overkill. Grass spiders are beneficial predators that eat mosquitoes, flies, and other pest insects. A combination of regular mowing, web removal, and sealing your home handles the problem for the vast majority of people without eliminating spiders you’d rather have working in your favor.