Getting rid of black widows in your garage requires a combination of removing their hiding spots, killing the spiders and their egg sacs directly, and sealing entry points so new ones can’t move in. Black widows are drawn to garages because they offer exactly what these spiders need: darkness, clutter, and a steady supply of insects to eat. The good news is that they’re no harder to treat than other spiders, and most homeowners can handle the job themselves unless the infestation is large.
Confirm You’re Dealing With Black Widows
Before you start treatment, make sure you’ve identified the spider correctly. Female black widows are shiny black with a red or orange hourglass marking on the underside of their round abdomen. Males are smaller, lighter in color, and not medically significant. The webs are another giveaway: black widow webs look messy and irregular, with no organized pattern, and they’re built low to the ground rather than in high corners like many other spiders.
Check dark corners, behind boxes stacked against walls, under workbenches, around stored equipment, inside old shoes or gloves, and along the base of garage walls. Black widows prefer ground-level hiding spots where they won’t be disturbed. If you spot round, cream-colored or tan egg sacs (roughly the size of a marble) hanging in the web, that’s a strong sign you have an established population. Each sac can contain hundreds of spiderlings.
Wear the Right Protective Gear
Black widow bites are serious. The venom attacks nerve endings in your muscles, causing intense, bodywide muscle pain and cramping. Children under 16 and adults over 60 face the highest risk of complications, including breathing and heart problems that may require hospitalization. You don’t want to reach blindly into a dark corner and get bitten.
Wear thick leather or heavy-duty work gloves, long sleeves, long pants tucked into boots or socks, and eye protection. Use a flashlight or headlamp so you can clearly see into every crevice before putting your hands near it. If you’re moving boxes or stored items, tap them first and check underneath before lifting.
Clear Out Clutter First
Clutter is the single biggest reason black widows thrive in garages. Cardboard boxes, stacked lumber, old tarps, piles of shoes, and rarely moved storage containers all create the dark, undisturbed spaces these spiders love. Before applying any treatment, pull everything away from the walls and sort through it. Move items you need into sealed plastic bins with tight lids. Get rid of anything you don’t actually use.
Sweep or vacuum behind and underneath shelving units, along baseboards, and in every corner. This step alone eliminates many of the webs, egg sacs, and spiders. Use a vacuum with a hose attachment to reach into crevices. If you vacuum up egg sacs, dispose of the vacuum bag immediately in an outdoor trash bin. For bagless vacuums, empty and clean the canister outdoors so spiderlings can’t escape inside your home.
Kill Black Widows With Targeted Treatment
Once the garage is decluttered and you can see what you’re working with, it’s time for chemical treatment. Insecticide dusts are more effective than liquid sprays for black widows because dust settles into cracks, voids, and crevices where spiders hide, and it stays active longer. Look for products containing deltamethrin, bifenthrin, cyfluthrin, or permethrin. Apply dust into electrical outlet gaps, switch plate covers, vent openings, and any wall voids using a handheld bellows duster for precise placement.
For broader coverage, use a residual liquid spray around window frames, door frames, the garage door track, mounted lights, and along the base of walls where the floor meets the wall. Spray the exterior foundation perimeter as well, extending a few feet out into the surrounding area. This creates a barrier that kills spiders trying to enter from outside.
If you find egg sacs during treatment, don’t just knock them down. Vacuum them up, or spray them directly with an insecticide labeled for spiders. Simply brushing an egg sac to the ground can scatter hundreds of tiny spiderlings across your garage floor.
Seal Entry Points Around the Garage Door
Killing the spiders already inside won’t help much if new ones keep walking in. Most garage doors leak in three places: the top seal, the side seals, and the bottom seal. Worn-out weatherstripping along these edges creates gaps large enough for spiders and the insects they feed on to pass through easily.
Inspect all three seals and replace any that are cracked, compressed, or missing. Pay special attention to the bottom seal, which takes the most wear. While you’re at it, check for gaps around:
- Utility penetrations: holes where cables, pipes, or conduit enter the garage wall
- Exhaust vents and air conditioning lines
- The junction between the garage foundation and siding
- Windows: both the frames and any cracked or missing caulk
Seal small gaps with caulk and larger ones with expanding foam or steel wool (for holes where rodents might also be an issue). The goal is to make the garage as tight as possible so spiders and their prey insects can’t get in.
Reduce What Attracts Them
Black widows move into your garage because food is available. They eat insects, and insects are drawn to light. If you have exterior lights mounted near the garage door or windows, they attract flying insects at night, which in turn attract spiders. Switch outdoor bulbs to yellow or warm-toned LED lights, which draw fewer insects. Or move lighting fixtures away from the garage entrance so bugs congregate farther from the door.
Inside the garage, reduce moisture wherever possible. Fix dripping faucets, improve ventilation, and avoid storing damp cardboard or fabric. Insects like crickets, earwigs, and silverfish thrive in moist environments, and they’re all black widow prey. Fewer prey insects means less reason for spiders to stay.
Keep the garage floor swept and organized on an ongoing basis. Black widows won’t build webs in areas that are regularly disturbed. If you use a section of the garage daily, spiders will avoid it. The forgotten corners, the shelf you haven’t touched in a year, the box behind the water heater: those are where they settle in.
When to Call a Professional
A single black widow or a few webs in the garage is something most people can handle with the steps above. But if you’re finding multiple spiders across different areas of the garage, discovering several egg sacs, or seeing spiders return repeatedly after treatment, a professional pest control service can apply commercial-grade products in hard-to-reach spots like wall voids, attic spaces above the garage, and crawlspaces underneath. They can also identify structural issues you might miss.
Professional treatment is also the safer choice if you have young children or elderly family members in the household, since black widow bites pose the greatest risk to those groups. If anyone in your home is bitten, seek medical attention right away. Typical treatment involves muscle relaxers for the severe cramping and pain medication. In serious cases, antivenom may be used to reverse the effects of the toxin.
Keeping Black Widows Gone Long Term
A one-time cleanout and spray won’t keep black widows away permanently. Reapply residual insecticide around the garage perimeter every few months, or according to the product label. Inspect weatherstripping seasonally, especially after temperature swings that cause materials to expand and contract. Do a quick flashlight sweep of corners and crevices every few weeks, particularly during warmer months when spider activity increases.
The combination of an organized, well-lit, sealed garage with periodic perimeter treatment makes the space inhospitable to black widows. They’ll move on to easier, darker, more cluttered spots, which is exactly the point.