A small, silky pouch stuck to your wall is almost certainly a spider egg sac, and most of the time it belongs to a harmless household species. These sacs can hold anywhere from a handful to several hundred eggs depending on the species, so identifying what you’re looking at helps you decide whether to leave it alone or remove it before the spiderlings emerge.
What Spider Egg Sacs Look Like
Spider egg sacs vary widely in appearance, but they share a few basics: they’re made of silk, they’re usually white or off-white, and they’re anchored to a surface or suspended nearby. Size ranges from a few millimeters across to roughly the size of a marble. Beyond those generalities, shape and texture are your best clues to what made it.
Smooth, round sacs are the most common. Many cobweb spiders and cellar spiders produce simple white or tan spheres, sometimes loosely wrapped in additional webbing. Flat, papery discs pressed against a wall likely come from smaller hunting spiders in the Phrurolithidae family. These feel almost like paper rather than silk. Cottony, irregular puffs that look like tiny cotton balls are typical of hammock spiders, a small species commonly found in basements and outbuildings.
If you see a silken tube or flat pouch in the upper corner where your wall meets the ceiling, you’re likely looking at a yellow sac spider retreat. These spiders build small silk tubes as daytime hiding spots and deposit their eggs inside during June or July. On light-colored walls and ceilings, these retreats blend in easily and can go unnoticed for weeks. The female stays nearby to guard the eggs, and after hatching, the spiderlings remain inside the tube briefly before venturing out at night to hunt.
Egg Sacs From Medically Significant Spiders
Two groups worth recognizing are widow spiders and brown recluses, since their bites can cause medical problems.
Brown widow egg sacs are the easiest to identify of any spider species. They’re round, yellow, and covered in small silk spikes, giving them a look often compared to a sea mine or a large pollen grain. No other common spider makes anything like them. You’ll typically find these tucked under house siding, patio furniture, or in sheds. Western black widow egg sacs, by contrast, are smooth and yellow, either perfectly round or slightly pointed at the top. Both types tend to be hidden in sheltered, undisturbed spots rather than on open walls.
Brown recluse egg sacs are harder to spot because they’re tucked inside the spider’s messy, woolly retreat. The sacs themselves look like small raised pillows nestled in fuzzy white silk. One useful trick: recluse silk glows brightly under a blacklight, so if you suspect recluse activity in a garage, attic, or closet, a UV flashlight can help you find retreats you’d otherwise miss.
How Many Spiderlings Are Inside
A single egg sac can contain anywhere from a few dozen to several hundred eggs. Some species produce one large sac, while others make multiple smaller ones over time, each with fewer eggs than the last. Wolf spiders, for example, typically carry 20 to 100 spiderlings per sac. Smaller house spiders tend toward the lower end, while larger orb weavers or widow spiders can pack several hundred eggs into a single sac.
Hatching timelines depend on species and temperature but generally range from two to four weeks after the eggs are laid. Warmer conditions speed things up. If you’ve found a sac and want to remove it before the spiderlings disperse, sooner is better than later.
How to Remove an Egg Sac Safely
The simplest and most effective method is vacuuming. Use a hose attachment, position it directly over the sac, and suck it up. If your vacuum uses a bag, remove the bag and dispose of it in an outdoor trash bin right away. For bagless models, empty and clean the canister outside. This keeps any spiderlings that have already hatched from escaping into your home.
If you don’t have a vacuum handy, use a broom or any long-handled tool to gently dislodge the sac from the wall. Collect it along with any surrounding webbing and dispose of everything outdoors. Wipe down the area afterward to remove residual silk, which can attract dust and signal to other spiders that the spot is a good nesting site.
Why Spraying Usually Doesn’t Work
Reaching for a can of bug spray is a natural instinct, but most household insecticides won’t kill the contents of an egg sac. Spider egg sac silk is highly water-repellent, and the vast majority of consumer sprays and professional pest-control products are water-based. The active ingredients kill spiders and eggs on contact just fine, but the liquid simply beads up on the silk surface and never reaches the eggs inside.
Research on brown widow egg sacs at the University of California, Riverside found that oil-based aerosol sprays were the exception. These penetrated the silk layer and completely prevented spiderlings from emerging. Water-based sprays from the same study performed poorly. If you do want to use a chemical approach, look specifically for an oil-based aerosol formulation rather than a pump spray or water-based product. But for a single egg sac on a wall, vacuuming or physical removal is faster, cheaper, and more reliable.
Preventing New Egg Sacs
Spiders choose wall locations that offer shelter, minimal disturbance, and access to prey like gnats, flies, and other small insects. Reducing those conditions makes your walls less attractive for egg-laying.
- Reduce outdoor lighting near entry points. Porch lights and lit windows attract flying insects, which in turn attract the spiders that eat them. Switching to yellow or warm-toned bulbs draws fewer insects.
- Seal gaps around windows, doors, and utility lines. Most indoor spiders entered through small openings rather than being carried in.
- Clear wall clutter. Egg sacs are most often found in corners, behind furniture, and along baseboards where spiders can build undisturbed. Regular dusting and vacuuming in these areas removes early-stage webs and retreats before egg-laying begins.
- Address moisture. Basements, bathrooms, and laundry rooms attract both insects and the spiders that hunt them. A dehumidifier or improved ventilation makes these spaces less hospitable.
A single egg sac on your wall is common and usually nothing to worry about. If you’re finding multiple sacs repeatedly, especially in areas like garages, crawl spaces, or storage rooms, that points to a larger spider population and a food source worth investigating.