Spider Eggs: What They Look Like and What to Do About Them

Finding spider eggs in your home can be alarming, especially when you consider that a single egg sac can contain hundreds of potential baby spiders. Understanding what spider eggs look like, where to find them, and how to deal with them is an important part of spider management.

What Do Spider Eggs Look Like?

Spider eggs are tiny — individual eggs range from 0.5 to 2 mm in diameter depending on the species. They are spherical, smooth, and typically cream, white, yellow, or pale green in color.

You will rarely see individual spider eggs. Female spiders wrap their eggs in silk to create protective egg sacs. The appearance of the egg sac varies by species:

• Round, papery balls: House spiders produce brownish, papery egg sacs suspended in their webs.
• White, smooth spheres: Black widows create smooth, round, cream-colored sacs.
• Fluffy or spiky sacs: Some species produce sacs with textured surfaces.
• Flat, disc-shaped sacs: Jumping spiders build flat silk retreats around their eggs.
• Carried sacs: Wolf spiders attach egg sacs to their spinnerets and carry them everywhere.

How Many Eggs Do Spiders Lay?

Egg count varies dramatically by species:

• House spiders: 100 to 400 eggs per sac, multiple sacs per lifetime.
• Black widows: 100 to 400 eggs per sac.
• Brown recluses: 40 to 50 eggs per sac.
• Wolf spiders: 100 to several hundred eggs per sac.
• Garden spiders: 300 to 1,400 eggs per sac.

Where to Find Spider Eggs

Spider eggs are typically laid in sheltered, undisturbed locations:

• Inside spider webs, especially cobwebs in corners
• Behind furniture, picture frames, and baseboards
• In closets, attics, and basements
• Inside stored boxes, especially cardboard
• Under eaves and overhangs outdoors
• In garages and storage sheds

How to Remove Spider Eggs

Vacuum Removal

The most effective method for indoor egg sac removal is vacuuming. Use a vacuum with a hose attachment to reach egg sacs in corners, ceiling junctions, and behind furniture. After vacuuming, immediately dispose of the vacuum bag or empty the canister into a sealed bag and place it in an outdoor trash can.

Manual Removal

If you can reach the egg sac, you can remove it by wrapping it in tissue and disposing of it in a sealed bag. Wear gloves if the egg sac belongs to an unidentified spider that could be a black widow or brown recluse.

Prevention

Preventing spiders from laying eggs indoors requires the same strategies used for general spider control:

• Reduce indoor spider populations using spider prevention tips.
• Regularly clean and vacuum sheltered areas.
• Seal entry points to keep spiders from entering in the first place.
• Use sticky traps to catch spiders before they can reproduce.

What Happens When Spider Eggs Hatch?

When eggs hatch, baby spiders (spiderlings) emerge from the sac. Depending on the species, this can mean dozens to hundreds of tiny spiders dispersing throughout your home. Spiderlings often "balloon" by releasing silk strands into air currents, which can carry them throughout the house.

If you find an intact egg sac, remove it promptly before hatching occurs. The spider life cycle from egg to adult varies by species but typically takes several months to a year.

When Spider Eggs Become a Problem

A single egg sac can seem insignificant, but consider the math:

• One female house spider can produce 10 to 15 egg sacs in her lifetime.
• Each sac may contain 100 to 400 eggs.
• That is potentially 1,000 to 6,000 eggs from a single spider.
• Not all will survive to adulthood, but even a small survival rate means dozens of new spiders.
• Those surviving spiders reproduce in turn, compounding the population growth.

This exponential potential is why removing egg sacs is one of the most impactful spider control actions you can take. Every sac you remove before hatching prevents hundreds of potential spiders from entering your living space.

Identifying Egg Sacs vs. Other Objects

People sometimes mistake other items for spider egg sacs:

• Insect cocoons: Usually more elongated and attached to a single surface. Moth cocoons are often fuzzy or rough-textured.
• Mud dauber nests: Made of mud rather than silk, with distinct tube shapes.
• Lint and dust bundles: Common in corners and ceiling junctions. These lack the structured, silk-wrapped appearance of egg sacs.
• Fungal growths: White or gray growths on surfaces in damp areas. These are usually fuzzy and attached to the surface rather than suspended in silk.

If you are unsure whether something is a spider egg sac, remove it anyway. If it is an egg sac, you have prevented a potential spider population explosion. If it is not, no harm done.

For more on spider management, see how to get rid of spiders and our complete guide to spiders.

Expert Insights

Spider egg management is a critical component of any effective spider control program. Throughout my 15 years as a BCE, I have emphasized to technicians and clients alike that removing adult spiders without addressing egg sacs is like mowing weeds without pulling the roots. During one memorable brown recluse treatment, we removed over 50 egg sacs from a single attic — each containing up to 50 eggs. Without addressing those sacs, the population would have rebounded within weeks. — Sarah Mitchell, BCE

Sources and References

• University of California Riverside Spider Research
• Burke Museum of Natural History and Culture
• Ohio State University Extension

Main Causes

Spiders lay eggs indoors when they have found stable harborage, adequate prey, and a sheltered location to reproduce. An indoor population that goes undetected for even one season can establish multiple egg-laying females. Cluttered storage areas — boxes, piles of clothing, stacked firewood stored inside — provide the undisturbed, dark conditions that female spiders seek for egg sac placement. According to UC IPM, the primary driver of indoor spider reproduction is prey abundance: where insects are plentiful, spiders follow. Gaps around windows, doors, and utility penetrations allow spiders to enter year-round, and basements, attics, and crawl spaces provide ideal overwintering habitat where females survive long enough to reproduce in spring. Penn State Extension notes that removing clutter and insect food sources is the most effective way to interrupt the spider reproductive cycle indoors.

How to Identify

Identification matters because risk and control differ significantly by species. Most household spiders — cellar spiders, common house spiders, jumping spiders, wolf spiders — are harmless and beneficial. Two species in North America warrant caution: the black widow with its shiny black abdomen and red hourglass marking, and the brown recluse with its violin-shaped marking and uniform tan-brown coloring without leg banding. Check webs for shape and structure: tangled cobwebs in corners indicate cellar or common house spiders; funnel-shaped webs near ground level indicate funnel-web species; sheet webs across grass are usually grass spiders. Single sightings without webs are usually transient outdoor species and do not indicate an infestation.

Risk and Severity

A single egg sac may seem minor, but the reproductive math is significant. A single house spider female can produce 10 to 15 egg sacs during her lifetime, each containing 100 to 400 eggs. Even a modest survival rate creates dozens of new adults, each capable of reproducing in turn. For harmless species, the primary risk is nuisance — webs, visible spiders, and sanitation concerns. For medically significant species, egg sacs represent a population expansion risk that compounds quickly. Black widow egg sacs in a garage or basement indicate a breeding female in the vicinity; her venom is a recognized health hazard per the CDC. Brown recluse egg sacs in storage areas suggest an established infestation that is difficult to eliminate without professional intervention. NPMA recommends immediate removal of all egg sacs and professional assessment when venomous species are suspected.

Solutions and Actions

For most spider species the goal is removing webs and reducing prey rather than chemical treatment. Vacuum or sweep down all visible webs weekly, including egg sacs, in garages, basements, attics, eaves, and exterior corners. Reduce indoor insect populations by maintaining screens, sealing entry points, and addressing any active pest issue — fewer insects means fewer spiders. Apply a residual insecticide barrier to the foundation perimeter, around windows and doors, and in eaves to deter newly arriving spiders. For confirmed black widow or brown recluse populations in storage areas, use professional pest control, wear long sleeves and gloves when handling stored items, and shake out shoes and clothing left in garages or basements. Single sightings indoors without webs are usually transient and need no chemical response.

Prevention

Preventing spider eggs indoors requires eliminating the conditions that allow female spiders to establish themselves. Seal gaps around doors, windows, pipe penetrations, and foundation vents to block entry routes. Reduce indoor insect populations — flies, moths, and other prey — through proper waste management, window screens, and targeted insect control. Vacuum corners, baseboards, and undisturbed storage areas regularly to remove webs and egg sacs before they mature. Declutter storage spaces: cardboard boxes and stacked fabric provide ideal egg-laying sites. According to UC IPM, sticky traps placed along baseboards and in storage areas catch spiders before they reproduce and provide useful population monitoring data. Store clothing, bedding, and seasonal items in sealed plastic bins rather than open shelving or cardboard. Check items brought in from sheds and garages, as egg sacs may hitchhike on outdoor equipment.

Frequently Asked Questions

What do spider eggs look like?

Individual spider eggs are tiny, round, and usually white or cream-colored. They are almost always enclosed in a silk egg sac rather than found individually. The egg sac's appearance varies by species — some are smooth and round, others are irregular or spiky. Most egg sacs are smaller than a dime.

How long does it take for spider eggs to hatch?

Spider eggs typically take two to four weeks to hatch, depending on the species and environmental conditions. Warmer temperatures generally speed up development. Some species' eggs overwinter and do not hatch until spring. After hatching, spiderlings may remain inside the sac for a short time before dispersing.

Can spider eggs hatch inside my house?

Yes. If a spider has laid eggs indoors, they can hatch inside your home. This is why removing egg sacs promptly is important. Vacuum up any egg sacs you find and dispose of the vacuum bag outdoors. Regular cleaning and reducing clutter helps prevent spiders from finding suitable sites to lay eggs indoors.

What should I recheck first for spider eggs?

Recheck the exact place, timing, and repeated signs connected with spider eggs before changing your plan. A single sighting or old web can mean something very different from fresh activity in several rooms. Confirm whether insects, clutter, moisture, gaps, or stored items are supporting the issue, then match the response to what you actually found.