Is the common house spider dangerous to kids or pets?

No. Parasteatoda tepidariorum is not medically significant. It bites only when pressed directly against skin, and even then produces at most minor local irritation — typically less than a mosquito bite. (Penn State Extension.) There are no systemic or neurological effects documented for this species in otherwise healthy people. Children and pets can be in the same room with house spiders without any meaningful risk.

How do I tell a house spider from a black widow?

Turn the spider over — or observe it from below if it is in the web — and look for a red or orange hourglass on the underside of the abdomen. Black widows have one; common house spiders do not. (bugswithmike.com; Penn State Extension.) The house spider is also mottled tan-to-brown (never glossy black), noticeably smaller, and builds a messy tangle cobweb rather than the widow's distinctive irregular web in low, sheltered spots. If you see no hourglass and a mottled brown pattern, it is almost certainly the harmless species.

Are house spiders common in New Hampshire?

Yes — Parasteatoda tepidariorum is one of the most common indoor spiders in North America and is found year-round in virtually every NH home, barn, garage, and outbuilding. (UF/IFAS Extension, Parasteatoda tepidariorum IN394.) It is strongly synanthropic — meaning it lives almost exclusively in human structures — and is active in all seasons because it does not depend on outdoor temperatures. If you have ever had a cobweb indoors in NH, it was almost certainly built by this species.

How do I get rid of house spiders?

The most effective approach is mechanical: vacuum webs and egg sacs (the tan papery pear-shaped sacs contain 200–300 eggs each), seal gaps and cracks around windows and the foundation, and reduce indoor insects that serve as food. (Penn State Extension.) Routine vacuuming every one to two weeks removes both adults and eggs before populations rebuild. Pesticide sprays have limited effectiveness against spiders sheltering in web corners and are generally unnecessary for this harmless species.

Why do new webs keep appearing after I clean them?

House spiders abandon disturbed webs and rebuild nearby within days. A single female can produce multiple egg sacs per year with 200–300 eggs each, so the local population replenishes quickly. (Penn State Extension.) Cleaning webs without removing egg sacs leaves the next generation in place. The most effective strategy is removing sacs during each cleaning, reducing indoor insects (the food supply), and sealing entry points so fewer spiders and prey insects can enter the building.

Do house spider bites hurt?

Rarely — and even then only mildly. The common house spider bites only when trapped or pressed against skin, and most reported bites produce nothing beyond minor local redness. (Penn State Extension.) The species is not considered medically significant by extension entomologists. It lacks the venom components that make widow or recluse bites dangerous. If you experience significant pain, swelling beyond the bite site, or systemic symptoms after any spider bite, consult a physician — but this species is not the expected cause.

What are the papery tan sacs in the spider's web?

Those are egg sacs — each one contains 200–300 eggs wrapped in tan papery silk. (Penn State Extension.) A female house spider can produce several sacs in her lifetime and guards them within the web. When cleaning, removing the sacs is as important as removing the web itself; leaving sacs behind means the population rebuilds within weeks regardless of whether you removed the adult spider. Dispose of the vacuum bag after cleaning to prevent hatched spiderlings from re-entering the home.

Should I get rid of house spiders or leave them?

House spiders are harmless and consume small insects, so a light population in out-of-the-way areas like basements and garages does no harm. Most homeowners prefer not to have cobwebs in living spaces, which is a reasonable aesthetic choice addressed by routine vacuuming. There is no safety reason to eliminate them, and no reason to use pesticides against a species this benign. The practical middle ground is regular mechanical removal of webs and sacs in occupied rooms while tolerating them in low-traffic areas.

Are house spiders a sign of a bigger pest problem?

Not directly — but a sudden increase in spider numbers can indicate a rising insect population inside the home, since spiders follow their food. (Penn State Extension.) If you notice more house spiders than usual alongside small flying insects or gnats, it may be worth checking for fruit fly or fungus gnat sources (overripe produce, overwatered plants, drains). Addressing the insect population reduces the spider's food supply and naturally reduces spider numbers without needing to target the spiders directly.

Common house spider · Parasteatoda tepidariorum

SpidersNH resident

House Spider in New Hampshire: ID, Webs & Control

Also called American house spider · Cobweb spider · Tangle-web spider

The common house spider (Parasteatoda tepidariorum) is the small mottled-brown cobweb spider responsible for most indoor webs in New Hampshire homes year-round. Despite surface-level similarity to black widows that drives many Google searches, it is harmless — no hourglass marking, minor bite risk, and not medically significant. The fastest way to rule out a black widow is to check the underside of the abdomen: no red or orange hourglass means it is almost certainly this harmless species.

At a glance

Female body size: 5–8 mm (sesame–peppercorn); male ~4–5 mm; UF/IFAS IN394
Hourglass?: None — NOT a black widow; bugswithmike.com; Penn State Extension
NH status: Present, very common year-round; synanthropic (lives in buildings); UF/IFAS Extension (IN394)
Bite risk: Rare and minor; Penn State Extension
Egg sac: Tan papery, 200–300 eggs/cycle; Penn State Extension

The short of it

The cobweb spider in your corners — harmless, and definitely not a widow

If you have found a small mottled-brown spider in the corners of your ceilings, basement, or garage, you almost certainly have the common house spider (Parasteatoda tepidariorum) — one of the most abundant and completely harmless spiders in New Hampshire. The one thing that sends people to pest control in a panic is the fear it might be a black widow, and the one check that resolves that fear immediately is looking for an hourglass: if the underside of the abdomen shows no red or orange hourglass marking, it is not a widow.

Parasteatoda tepidariorum belongs to the family Theridiidae (cobweb spiders), the same family as widows — which is why the webs look similar. But the similarities end there. The house spider is much smaller, has a mottled tan-to-brown chevron pattern with no glossy black, and builds its irregular tangled cobwebs in sheltered indoor corners where it waits for small insects.

In southern New Hampshire these spiders are active year-round inside climate-controlled buildings. The papery tan egg sacs they park in the web — each containing 200–300 eggs — are the main reason populations rebuild quickly after cleaning.

Identify it

How to identify the common house spider

Three features separate the house spider from the spiders people fear: the absence of any red or orange hourglass, the small mottled body pattern, and the irregular tangled cobweb rather than an orb or flat sheet. The hourglass check is the most important — do it on the underside of the abdomen.

Species profile

Common house spider

Scientific name: Parasteatoda tepidariorum
Family: Theridiidae
Size: Female 5–8 mm; male 4–5 mm
Coloration: Mottled tan to medium brown with darker chevron/stripe pattern on abdomen; NOT glossy black. Legs banded brown and cream.
Habitat: Indoor and sheltered outdoor spots — ceiling corners, window frames, basements, garages, barns, crawlspaces, and under eaves.
Active season: Year-round indoors in New Hampshire; does not require warm temperatures.
Diet: Small insects and other arthropods that blunder into the irregular tangle web.
Reproduction: Produces multiple egg sacs per year, each containing 200–300 eggs wrapped in tan papery silk; female guards sacs in the web.
Lifespan: Females can live over a year; males shorter-lived.

Cosmopolitan worldwide; one of the most common indoor spiders across North America including all of New Hampshire.

The tells — key ID features

Round abdomen with mottled tan-to-brown chevron pattern and NO red or orange hourglass — the most critical distinguishing feature.
Tan papery pear-shaped egg sacs parked inside the web — often the most visible part of the nest.
Messy, irregular tangle cobweb in sheltered corners — no geometric orb or funnel shape.
Variable coloration from pale tan to medium brown; never glossy black like a widow.
Frequently abandons and rebuilds webs in slightly different spots nearby when disturbed.
Small body — sesame seed to peppercorn in size — versus the larger, stouter body of a widow.

Size, to scale

The insect

Female 5–8 mm; male 4–5 mm

Compared to

Body about the size of a sesame seed (small female) to a peppercorn (large female)

Looks bigger than it is

People often overestimate the size of house spiders when alarmed — the body is typically no larger than a small pea.

Is it actually this? — the confusion species

Northern black widow (Latrodectus variolus)

How to tell — Black widows are glossy jet-black with a red or orange hourglass on the underside of the abdomen; house spiders are mottled brown with NO hourglass. Widows are rare in NH.

False widow (Steatoda spp.)

How to tell — Darker brown, rounder abdomen, no hourglass; same family as the house spider but slightly more robust. Harmless.

Triangulate cobweb spider (Steatoda triangulosa)

How to tell — Has a distinctive triangular pattern on the abdomen; similar messy web; also harmless.

What you'll notice

Signs of a problem

The house spider leaves consistent calling cards. These signs tell you what you have — and how active the population is.

Multiple short-lived cobwebs appearing in ceiling corners, window frames, and basement areas

What it means — An active house spider population tracking small insect prey; frequency of new webs signals population size.

Tan papery pear-shaped egg sacs clustered in or near the web

What it means — A breeding female; removing sacs mechanically is more effective than spraying.

Small mottled brown spider in a corner web with no red or orange hourglass visible

What it means — Almost certainly the harmless common house spider — the defining check is the absent hourglass.

Webs in basements, crawlspaces, or damp garage corners

What it means — House spiders favor humid, sheltered spots with reliable insect traffic; damp areas support both the spider and its prey.

Web abandoned and rebuilt slightly differently nearby within days

What it means — House spiders frequently move short distances when webs are disturbed; the population is not gone, just relocated.

How much it matters

The real risks, calibrated

The common house spider is harmless to people and pets. Its only practical downside is the aesthetic of cobwebs in living spaces.

Overall risk

Low risk

Defensive bite if pressed against skin

Low risk

Onset: Immediate

Minor local irritation — typically less severe than a mosquito bite. Not medically significant; no systemic effects documented for this species.

Cosmetic cobweb accumulation

Low risk

Onset: Over days to weeks

Ongoing web-building in corners and window frames requires routine vacuuming; heavy populations can make spaces appear neglected.

What you can do

DIY — what works, what backfires

House spider control is maintenance work, not an emergency. The goal is reducing prey, removing webs and egg sacs mechanically, and sealing entry points so fewer spiders and insects can enter. Here is what works — and what to skip.

What actually works

Vacuum webs and egg sacs thoroughly — including the tan papery sacs, which contain 200–300 eggs each; dispose of the vacuum bag promptly.
Reduce indoor insects (the spiders' food supply) by fixing window screens, sealing door gaps, and reducing lighting that draws moths.
Seal cracks and gaps around windows, pipes, and the foundation to reduce spider entry from outside.
Control moisture in basements and crawlspaces — damp areas support both house spiders and the insects they eat.

What backfires

Don't mistake a mottled brown house spider for a black widow — check for the absent hourglass before taking any action.
Don't fog or bomb a room for a spider this harmless — aerosol space treatments rarely reach sheltered web sites and are unnecessary.
Don't ignore egg sacs when cleaning webs; leaving sacs behind means the population rebuilds within weeks.
Don't assume repeated new webs mean a fresh invasion — the same small population just keeps rebuilding locally.

Local Context

House spiders in New Hampshire homes, barns, and basements

Parasteatoda tepidariorum is one of the most synanthropic spiders in the world — it thrives almost exclusively in and around human structures. In southern NH it is present year-round in Manchester, Nashua, Concord, and every town in between: basements, crawlspaces, garage corners, window frames, and the upper corners of bedrooms and barns. Unlike seasonal outdoor spiders, it does not depend on warm weather; a damp basement provides everything it needs in January.

Peak season

Year-round indoors; no true peak season in climate-controlled buildings

You might actually have

Cellar spider / daddy longlegs (Pholcus phalangioides — long wispy legs, pulsating defense behavior)
Northern black widow (Latrodectus variolus — glossy black, red hourglass, rare in NH)
False widow (Steatoda spp. — darker, rounder, no hourglass)

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Southern New Hampshire

When it's past DIY

When to call a pro for house spiders

Isolated house spiders rarely need professional treatment. If you are seeing persistent cobweb buildup throughout the home despite regular cleaning, have difficulty ruling out a black widow, or want a general spider treatment for the exterior perimeter, Anchor Pest Services can help.

Signals it's past DIY

When to call a pro

Persistent cobweb buildup throughout the home despite regular vacuuming and cleaning.
You cannot confidently rule out a black widow or other medically significant spider and want a professional ID.
You want a perimeter spider treatment to reduce the overall spider population entering the home.
Heavy populations in a crawlspace, basement, or outbuilding that you cannot easily access.

Keep them out — prevention

Vacuum routinely including corners and window frames

Regular mechanical removal of webs and egg sacs is the most effective single step; aim for every two weeks in active areas.

Seal gaps and entry points

Caulk gaps around windows, pipes, and the foundation. Install door sweeps. Reducing entry points cuts both spider and insect (prey) populations.

Control nuisance insects indoors

House spiders follow their food. Fixing window screens, replacing white exterior bulbs with yellow LED lights, and keeping drains clean all reduce the insect supply that sustains spider populations.

Not sure it's a common house spider?

A licensed NH technician can confirm the species and tell you honestly whether it's a DIY fix or a job for a pro — free inspection, same-day service across Southern New Hampshire.

Get a Free Inspection (603) 785-0118

Common Questions

Frequently asked questions

Sources(3)

[1]
UF/IFAS Extension — Parasteatoda tepidariorum (IN394)
body size, identification, biology, synanthropic status, cosmopolitan range
extensionverified 2026-06-30
[2]
Penn State Extension — Common House Spider
egg sac (200–300 eggs), bite risk, identification, control
extensionverified 2026-06-30
[3]
Bugs With Mike — House Spider vs. Black Widow
hourglass absence as widow distinguishing feature
educationalverified 2026-06-30

Written & reviewed by

Verified

Daniel Brady

NH-Licensed Pesticide Applicator · License #782664 (NHDAMF, RSA 430)

Daniel Brady is the New Hampshire–licensed applicator behind Anchor Pest Services, a family-owned pest control company serving the Manchester area since 2017.

Verify license

Last updated 2026-06-30

New Hampshire pest control

Dealing with common house spiders in your home?

Anchor Pest Services identifies and handles common house spider problems across southern and central New Hampshire. Family-owned since 2017, NH license #782664.

Get a Free Inspection (603) 785-0118

NH-licensed applicators (#782664)
Same-day service · free inspection
Family-owned since 2017

Keep Exploring

House Spider in New Hampshire: ID, Webs & Control

The cobweb spider in your corners — harmless, and definitely not a widow

How to identify the common house spider

The tells — key ID features

Size, to scale

Northern black widow (Latrodectus variolus)

False widow (Steatoda spp.)

Triangulate cobweb spider (Steatoda triangulosa)

Signs of a problem

Multiple short-lived cobwebs appearing in ceiling corners, window frames, and basement areas

Tan papery pear-shaped egg sacs clustered in or near the web

Small mottled brown spider in a corner web with no red or orange hourglass visible

Webs in basements, crawlspaces, or damp garage corners

Web abandoned and rebuilt slightly differently nearby within days

The real risks, calibrated

Defensive bite if pressed against skin

Cosmetic cobweb accumulation

DIY — what works, what backfires

What actually works

What backfires

House spiders in New Hampshire homes, barns, and basements

When to call a pro for house spiders

Vacuum routinely including corners and window frames

Seal gaps and entry points

Control nuisance insects indoors

Not sure it's a common house spider?

Frequently asked questions

Dealing with common house spiders in your home?

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