Spider Eggs and Egg Sacs and Spiderlings, Oh My!

This wolf spider's hatchlings cling to her back after emerging from the egg sac at her rear. Iain Lawrie / Getty Images

Let's talk about spider eggs, those tiny wonders of nature that hold the next generation of arachnids.

Spider egg sacs, made of silk, are carefully crafted by mom spiders to protect their baby spiders as they grow and develop. While they might seem a little creepy at first, these sacs are an incredible example of spider survival strategies.

These egg sacs are found in a variety of places and often contain dozens — or even hundreds — of spiderlings ready to emerge.

What Do Spider Eggs Look Like?

spiky white balls surrounded by web — Brown widow spider egg sacs. Jay Ondreicka / Shutterstock

You're more likely to spot egg sacs than the spider eggs themselves. Spider egg sacs (not "egg sacks") are small, round or teardrop-shaped bundles made of silk. They're often white, cream or pale yellow.

These sac of a common house spider is typically about the size of a small marble or a pea, but sac size varies depending on the species. The silk sac of a garden spider is slightly larger and more robust, while the sac of a brown widow spider is smaller and spikier.

Inside the sac, a female spider may lay anywhere from a few dozen to hundreds of eggs. They're designed to protect the baby spiders from predators, keeping them warm and safe from harsh conditions until they're ready to emerge.

When spiderlings hatch, they may stay close to their mom spider or disperse into their surroundings using silk lines.

Where Do Spider Eggs Commonly Appear?

Spider egg sacs can show up in a surprising variety of locations. Many species of house spiders create their sacs in hidden corners, under furniture or tucked away in closets. Resident spiders in basements or attics might place their sacs along walls or ceilings, using their own webs to secure them in place.

Outdoors, other spiders often hide their eggs in leaf litter, under rocks or attached to plant stems.

Wolf spiders carry their egg sacs attached to their abdomen, ensuring their babies stay warm and protected wherever they go. Widow spiders — like black widows — hide their egg sacs in dark, quiet spots like woodpiles or sheds.

What to Do If You Find Spider Eggs in Your House

First, don't panic. Spider egg sacs are completely harmless, even if their future occupants might make you uneasy. If you're okay with spiders and appreciate their role as natural pest controllers, you can leave the sac alone. You can let the babies hatch and move on, helping to control insect populations in and around your home.

If you'd rather not share your space with spiderlings, carefully remove the sac using a tissue, broom or vacuum. Be sure to check for more sacs nearby, as many species of spiders lay multiple sacs in one location.

For venomous spiders like black widows, consider contacting pest control to safely remove the sacs and adult spiders.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.