Is the black widow dangerous to children or pets?

Yes — with important context. The northern black widow's neurotoxin (latrodectism) is medically significant, and children and small pets face greater risk from a given dose of venom than healthy adults. That said, bites are genuinely rare: the spider avoids confrontation and bites only when accidentally pressed against skin. Symptoms — muscle cramps, abdominal rigidity, sweating — appear within an hour. Any suspected bite in a child should prompt an immediate visit to the emergency room; call NNEPC (1-800-222-1222) for triage guidance. No US death from a widow bite has been recorded since 1983.

Is the black widow actually found in New Hampshire?

Yes — the northern black widow (Latrodectus variolus) is present in southern and coastal New Hampshire, though it is genuinely uncommon. It favors undisturbed outdoor harborage: stone walls, woodpiles, fieldstone foundations, and the corners of unheated sheds. The NH population sits at the northern edge of the species' range, and research indicates widows struggle to survive NH winters in unheated buildings. Your odds of encountering one are low but not zero — especially if you have active woodpiles or old fieldstone walls on your property.

How do I identify a black widow?

Look for three things in order: first, a glossy jet-black, round abdomen — not brown, not mottled; second, the spider hanging upside-down in a messy, irregular, low-to-the-ground web (not an orb web); and third, a red hourglass on the underside of the abdomen, which in the northern species is often split into two separate spots rather than a complete shape. Body size is roughly that of a pea. If you cannot see the underside, do not assume. A photograph sent to a pest professional or UNH Cooperative Extension can confirm the ID.

What are the signs of a black widow in my woodpile or shed?

The most reliable signs are the web and egg sac rather than the spider itself. A black widow builds a tangled, irregular web very close to the ground — a few inches up in a woodpile crevice or along a foundation — not the tidy circular orb of a garden spider. Inside or near the web, look for a papery tan egg sac roughly marble-sized with a slightly bumpy surface. The spider itself hangs upside-down in the web and is shy; you are far more likely to find a web and egg sac than to spot the spider directly.

How fast do black widow bite symptoms appear?

Symptoms typically begin within 30 minutes to a few hours of a bite. Early signs include local pain at the bite site, followed by spreading muscle cramps — classic latrodectism involves painful abdominal cramping that can mimic appendicitis. Sweating, nausea, elevated blood pressure, and tremors can follow. Symptoms generally peak within the first 24 hours and resolve over 3–7 days with supportive medical care. Anyone who suspects a widow bite should call Poison Control (NNEPC 1-800-222-1222) immediately and seek physician evaluation — do not wait for symptoms to worsen.

Will a black widow bite me if I get near it?

Almost certainly not. Black widows are defensive, not aggressive — they flee when disturbed and bite only when accidentally pressed against skin, such as when a person reaches bare-handed into a woodpile or puts on a shoe left in a garage. The vast majority of bites happen because the spider was trapped against the person with no escape route. If you see a widow in the open, it will run. Avoiding accidental contact — wearing gloves, shaking out footwear, being careful around woodpiles — eliminates most meaningful risk.

How big is a black widow? Will I notice it?

A female northern black widow's body is about 13 mm (roughly ½ inch) — the size of a pea. That makes her noticeably larger than a cellar spider but smaller than many people expect given the reputation. The long, shiny black legs make her appear larger than the body measurement suggests. Males are roughly half the female's size and have brownish or spotted coloration rather than solid glossy black. In practical terms, you would notice a female widow if you were looking carefully, but could easily overlook one in the dark gap of a woodpile without deliberately checking.

Can a male black widow bite or hurt me?

No. Male black widows cannot envenomate humans — their chelicerae (fangs) are too small to penetrate human skin, and male venom potency is negligible even in the rare case of contact. Only the adult female poses any bite risk. Males are also rarely encountered: they are smaller, brownish or mottled rather than glossy black, and typically die shortly after mating. If you find a glossy jet-black, round-bodied spider with a red underside mark, it is female. Males are not a practical envenomation concern for NH residents.

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

Four quick differences: (1) Color — widows are glossy jet-black with no mottling; house spiders are tan, brown, or yellowish with a spotted or striped pattern. (2) Abdomen — widows have a large, perfectly round, globe-like abdomen; house spiders are smaller and more oval. (3) The hourglass — only widows have a red mark on the underside; house spiders have none. (4) Web location — widows build messy webs within inches of the ground; house spiders build higher, in wall corners and window frames. If the spider is glossy black and round, check the underside before concluding.

What is latrodectism and how is it treated?

Latrodectism is the clinical syndrome caused by black widow venom — specifically by alpha-latrotoxin, a neurotoxin that overwhelms nerve junctions, triggering sustained muscle excitation. Symptoms include intense muscle cramps (especially of the abdomen and back), pain spreading from the bite site, sweating, elevated blood pressure, nausea, and tremors. Treatment is supportive: pain management, muscle relaxants, and monitoring in a medical setting. Antivenom is available for severe cases. Symptoms typically resolve in 3–7 days. Anyone bitten should contact Poison Control (NNEPC 1-800-222-1222) and seek evaluation by a physician promptly.

Northern Black Widow · Latrodectus variolus

SpidersRare in NH

Black Widow Spider in New Hampshire: ID, Risk & Control

Also called Northern widow · Widow spider

The northern black widow is the only New Hampshire spider with medically significant venom — but it is shy, uncommon, and almost always flees rather than bites. A female's glossy black body and split red hourglass mark are the fast ID, and symptoms (muscle cramps, pain) begin within an hour and last 3–7 days but are treatable; no US death has been recorded since 1983.

At a glance

Female body size: ~½ inch (13 mm); males half that & can't envenomate; Rutgers NJAES FS1121
Symptom onset: 30 min–few hours after bite; University of Utah Poison Control
US deaths since 1983: None recorded; 2012 AAPCC review; Penn State Extension
NH status: Present but uncommon (southern NH); Latrodectus variolus; MSU Extension
Hourglass: Often split into two spots (northern); MSU Extension
Venom type: Neurotoxin (latrodectism); NIH StatPearls NBK499987

The short of it

NH's only medically significant spider — and it's genuinely rare

The northern black widow (Latrodectus variolus) is the only New Hampshire spider whose venom is considered medically significant — but the reputation requires calibration. It is shy, uncommon in NH, almost never bites without extreme provocation, and has not caused a documented death in the United States since 1983. The honest starting point is: medically relevant, yes; routine danger to NH residents, no.

Identification is fast if you know the two key marks: a glossy, jet-black, pea-sized round abdomen and a split red hourglass (often two separate spots rather than a joined shape) on the underside of the abdomen. The web is equally distinctive — messy, irregular, and built just inches off the ground inside woodpiles, sheds, and crawlspaces, nothing like the tidy orb of a garden spider.

In New Hampshire the northern black widow is most likely to turn up in southern and coastal areas, sheltering in stone walls, fieldstone foundations, woodpiles, and undisturbed outdoor corners. The risk frame matters: the spider's venom is a genuine neurotoxin that causes painful muscle cramps and can require medical treatment, but symptoms are treatable and males — half the size and typically brownish — cannot envenomate humans at all. A confirmed sighting warrants respect and caution, not panic.

Identify it

How to identify a northern black widow

Three features clinch the ID in order of reliability: the split red hourglass on the underside, the glossy jet-black round abdomen, and the tangled irregular web built low to the ground. All three together are definitive; none alone is sufficient.

Species profile

Northern Black Widow

Scientific name: Latrodectus variolus
Family: Theridiidae
Size: Female ~13 mm (½ inch); male ~6 mm
Coloration: Female: glossy jet-black; red hourglass (often split into two spots) on underside of abdomen. Male: smaller, brownish or spotted, less distinctive.
Habitat: Stone walls, woodpiles, outdoor sheds, crawlspaces, and fieldstone foundations — low to the ground, undisturbed, and dark.
Active season: Warm months outdoors; may shelter indoors year-round in enclosed harborage
Diet: Insects caught in irregular tangled webs
Reproduction: Female lays 100–400 eggs per papery tan egg sac; multiple sacs possible per season
Lifespan: Female up to 3 years; male much shorter

Southern and coastal New Hampshire at the northern edge of species range; wider range in southern and coastal US.

The tells — key ID features

Split or incomplete red hourglass on underside of abdomen — the single definitive ID mark (turn the spider over or see it hanging inverted).
Glossy, jet-black, round globe-like abdomen — unlike any other NH spider.
Irregular, messy tangled web built very low (inches off the ground) in woodpiles, sheds, and crawlspaces.
Hangs upside-down (inverted) in the web at rest.
Flees rather than attacks — bites almost always result from accidental contact or being trapped against skin.
Papery tan egg sac inside or near the web, roughly marble-sized.

Size, to scale

The insect

Female ~½ inch (13 mm) body

Compared to

About the size of a pea — long shiny black legs make the spider appear larger

Looks bigger than it is

Males are roughly half this size, brownish rather than glossy black, and cannot envenomate humans.

Is it actually this? — the confusion species

False widow (Steatoda spp.)

How to tell — Similar dark round abdomen but no red hourglass — Steatoda has pale spots or bands instead. Not medically significant.

Common house spider

How to tell — Mottled tan or brown coloration; no glossy black body; no hourglass marking. Found in similar areas but completely harmless.

Cellar spider

How to tell — Extremely long thin legs with a tiny pale body — no resemblance to the stout black widow. Harmless.

What you'll notice

Signs of a problem

Black widows are more likely to be detected by their web and egg sac than by the spider itself, which hides in dark undisturbed corners. These signs point to widow activity near a woodpile, shed, or foundation.

Tangled, irregular web built very low (a few inches off the ground) in a woodpile, shed, or crawlspace

What it means — The messy, non-orb structure is distinctive — not the regular circular web of a garden or orb-weaver spider.

Papery tan egg sac inside or near a tangled web at ground level

What it means — Widow egg sacs are papery and slightly spiky, roughly marble-sized — often the first discoverable sign inside a crawlspace or foundation void.

Glossy black spider hanging upside-down in the web

What it means — The inverted resting posture combined with the jet-black coloration are immediate red flags — confirm the split red hourglass on the underside before concluding.

How much it matters

The real risks, calibrated

The northern black widow is NH's only spider with venom of medical concern. Bites are rare, almost always result from accidental contact, and have not caused a US death since 1983. For any suspected bite, contact NNEPC at 1-800-222-1222 or seek physician evaluation.

Overall risk

Severe

Latrodectism (neurotoxin envenomation)

Severe

Onset: 30 minutes to a few hours after bite

Muscle cramps and spasms (especially abdomen), pain spreading from the bite site, sweating, nausea, abdominal rigidity, and elevated blood pressure. Symptoms typically peak at 24 hours and resolve over 3–7 days with supportive care. Contact NNEPC (1-800-222-1222) or see a physician immediately for any suspected widow bite.

Misidentification (unnecessary alarm)

Low risk

Onset: Immediate

Most 'black widows' reported in NH are harmless species — false widows, house spiders, or orb-weavers. Confirm the split red hourglass before escalating.

What you can do

DIY — what works, what backfires

Black widow control is more about reducing harborage and exposure than chemical treatment. Most meaningful prevention happens outdoors before the spider ever comes close to living areas.

What actually works

Wear heavy leather gloves when moving firewood, stacked lumber, or stones — the most common bite situation.
Store firewood at least 20 feet from the house and keep it elevated off the ground.
Reduce clutter and debris piles in sheds, garages, and crawlspaces to eliminate undisturbed harborage.
Shake out gloves, shoes, and clothing left in garages or sheds before wearing.
If you find a widow, trap it in a sealed jar for professional or extension confirmation — then decide on next steps.

What backfires

Never probe a web or dark woodpile corner with a bare or gloved hand — use a stick or broom handle first.
Don't assume every glossy black spider is a widow — check the underside for the split red hourglass before alarming the household.
Don't ignore a confirmed egg sac indoors — a single sac can contain 100–400 eggs.

Local Context

Black widow activity in southern New Hampshire

The northern black widow reaches the edge of its range in southern and coastal New Hampshire. It is not a common backyard spider — it shows up in specific harborage conditions: gaps in fieldstone foundations, the dark interior of woodpiles, undersides of rocks or stacked timber, and the corners of unheated outdoor sheds. Activity peaks from late spring through early fall, but a widow sheltered in an enclosed crawlspace or wall void can persist through NH winters. Most residents are unlikely to encounter one unless actively disturbing these harborage sites; a confirmed sighting is unusual enough to warrant professional follow-up.

Peak season

Warm months outdoors; harborage year-round in enclosed spaces

You might actually have

Cellar spider (long-legged, pale — harmless)
Common house spider (tan/brown mottled — harmless)
Wolf spider (large, ground-hunting — harmless)

We serve these communities

ManchesterBedfordSalemDerryAuburn

Rockingham · Hillsborough Counties

NH-licensed applicator · #782664
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Service Area Map

Southern New Hampshire

When it's past DIY

When to call a pro for black widows

A confirmed widow near a woodpile or foundation is not an emergency, but repeated sightings or egg sacs inside living areas warrant a professional inspection to locate harborage and reduce ongoing risk.

Signals it's past DIY

When to call a pro

Repeated widow sightings near the foundation, woodpile, or crawlspace access point.
An egg sac found inside the home, attached garage, or finished crawlspace.
Young children or pets regularly play near suspected harborage sites.
You are not confident in your ID — have a professional confirm before escalating treatment.

Keep them out — prevention

Relocate woodpiles away from the foundation

Move stacked firewood and lumber at least 20 feet from the house and elevate it off the ground — this removes the single most common black widow harborage in NH.

Seal foundation cracks and crawlspace entries

Fill gaps in fieldstone foundations, sill plates, and crawlspace entries to block harborage points and reduce spider access to the home interior.

NH-specific

Adopt the gloves-and-shake-out habit

Make heavy gloves standard for outdoor work around sheds and woodpiles, and shake out shoes and gloves that have been left in unheated spaces.

Not sure it's a northern black widow?

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(6)

[1]
Rutgers NJAES — Black Widow Spider FS1121
female/male size; male cannot envenomate
extensionverified 2026-06-30
[2]
NIH StatPearls — Latrodectism (NBK499987)
venom mechanism, symptom onset, clinical presentation
govverified 2026-06-30
[3]
University of Utah Poison Control — Black Widow
symptom onset 30 min–few hours; duration 3–7 days
govverified 2026-06-30
[4]
Penn State Extension — Black Widow Spiders
US bite statistics; no deaths since 1983 (2012 AAPCC review)
extensionverified 2026-06-30
[5]
MSU Extension — Northern Black Widow Spiders in Michigan
hourglass often split in northern species; northern-species range notes including NH
extensionverified 2026-06-30
[6]
Colonial Pest Control — Black Widow in New England
widows dying over NH winter in unheated buildings (Tillinghast research)
industryverified 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.

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Last updated 2026-06-30

New Hampshire pest control

Dealing with northern black widows in your home?

Anchor Pest Services identifies and handles northern black widow problems across southern and central New Hampshire. Family-owned since 2017, NH license #782664.