What most people call a “spider nest” is actually an egg sac, a small silk pouch that a female spider builds to protect her eggs until they hatch. Finding one in your house means a spider has been living and reproducing nearby, and depending on the species, a single sac can hold anywhere from 50 to 250 baby spiders. The good news: most egg sacs are easy to remove safely, and a few preventive steps can keep spiders from nesting indoors again.
What Spider Egg Sacs Look Like
Spider egg sacs vary by species, but they share some basics. They’re made of silk, typically round or teardrop-shaped, and range from about the size of a pea to roughly the size of a marble. Color runs from white or cream to tan or yellow depending on the spider. You’ll usually find them tucked into corners, along ceiling edges, behind furniture, inside closets, in garages, or near windows where a web is already present.
Common house spiders build small, round, off-white sacs that often hang within their messy cobwebs. You might spot several in one area because a single female can produce multiple sacs over her lifetime, each holding up to 250 eggs. These sacs are the ones most people encounter, and they’re harmless.
Black widow egg sacs are round (sometimes pointed at the top), yellow, and smooth to the touch. You’ll typically find them in dark, undisturbed spots: garages, crawl spaces, sheds, and behind stored boxes. Brown recluse egg sacs are smaller, less than an inch across, and contain roughly 40 to 50 tiny yellow eggs wrapped in sticky, irregular silk. Brown recluses don’t build the classic circular web. Instead, they create flat, messy silk “retreats” in hidden areas like cardboard boxes, seldom-used drawers, and behind wall hangings. The female uses this retreat silk to form her egg sac, so the sac may be partially hidden within a loose tangle of threads.
How Quickly They Hatch
For common house spiders, eggs typically hatch within about a week. The spiderlings that emerge are tiny and nearly translucent, and they go through several molts before reaching adult size. Other species take longer. Brown recluse eggs can take about a month to hatch, while black widow eggs generally hatch in two to four weeks depending on temperature.
This timeline matters because it determines how urgently you need to act. A sac you found yesterday probably still contains eggs. One that’s been sitting undisturbed in a corner for weeks may have already released its spiderlings. If you notice a sac that looks torn open or has a visible hole, the babies have likely already dispersed.
How to Remove an Egg Sac Safely
The most reliable method is vacuuming. Use a hose attachment to reach the sac, suck it up, and immediately take the vacuum bag outside to a sealed trash bin. If you have a bagless vacuum, empty and clean the canister outdoors rather than inside. This prevents any spiderlings that may have already hatched from escaping into your home.
If you don’t have a vacuum handy, a broom or any long-handled tool works. Dislodge the sac, sweep it into a bag, and dispose of it outside. Afterward, wipe down the area to remove any remaining silk or egg residue.
For chemical options, the type of product matters more than most people realize. Research published in the Journal of Economic Entomology found that water-based pesticide sprays are largely ineffective against egg sacs because spider silk is highly water-repellent. The liquid simply beads off the surface without reaching the eggs inside. Oil-based aerosol pesticides, on the other hand, penetrate the silk and completely prevent spiderlings from emerging. Since most household pesticide sprays are water-based, check the label before assuming a quick spray will solve the problem. A diluted bleach solution can also help sanitize the area after physical removal.
If you’ve identified the sac as belonging to a black widow or brown recluse, professional pest control is the safer route. Disturbing the nest of a venomous spider creates a risk you don’t need to take on yourself.
Why Spiders Nest Indoors
Spiders move inside for three reasons: food, shelter, and easy access. If your home has other small insects like gnats, flies, or ants, spiders follow the food supply. Cluttered, undisturbed spaces give them exactly the quiet, dark environment they prefer for egg-laying. And most homes have more entry points than people realize.
Gaps as small as 1/16 of an inch under a door are enough for spiders and their insect prey to slip through. Cracks around windows, torn screens, openings where pipes and wires enter the foundation, and unsealed garage doors all serve as open invitations.
Preventing Spiders From Nesting Again
Sealing entry points is the single most effective long-term strategy, and it protects against far more than just spiders. Start with the gaps that let in the most pests:
- Exterior doors: Install door sweeps on every outside door. Lie on the floor and look for light coming through underneath. Apply caulk along the bottom edge and sides of door thresholds.
- Windows: Caulk cracks around window frames using silicone or acrylic latex caulk. Repair any torn or damaged screens.
- Garage doors: Fit them with a rubber bottom seal (vinyl tends to crack and fail in cold weather).
- Sliding glass doors: Line the bottom track with half-inch to three-quarter-inch foam weatherstripping to close the gap.
- Utility openings: Seal every spot where pipes, wires, faucets, dryer vents, and cable lines pass through your foundation or siding. Caulk, expandable foam, steel wool, or copper mesh all work depending on the size of the gap.
- Vents: Cover attic, roof, and crawl space vents with quarter-inch wire mesh to block not just spiders but also rodents and wildlife.
Inside the house, reduce clutter in storage areas, basements, and garages. Cardboard boxes sitting on the floor are a favorite hiding spot for brown recluses in particular. Switching to sealed plastic bins and keeping them off the ground eliminates prime nesting real estate. Regular vacuuming along baseboards, in corners, and behind furniture removes both webs and any newly deposited egg sacs before they hatch.
For an added layer of protection, an exterior barrier treatment with a liquid insecticide applied around the foundation can help. Spray at the base of all exterior doors, around garage and crawl space entrances, near foundation vents and utility openings, and in a band two to six feet wide along the ground at the foundation perimeter. This creates a chemical buffer zone that kills spiders and insects before they find their way inside.
One Egg Sac vs. an Infestation
A single egg sac in an otherwise clean home is normal and nothing to panic about. Spiders are opportunistic, and even well-sealed houses occasionally get a visitor. Remove the sac, check the surrounding area for others, and move on.
Multiple egg sacs in different rooms, frequent spider sightings, or sacs belonging to venomous species suggest a bigger issue. In those cases, a pest control inspection can identify the species, locate hiding spots you’ve missed, and apply targeted treatments (including the oil-based products that actually penetrate egg sacs) in areas you can’t easily reach yourself.