# Northern black widow (Latrodectus variolus) > A small, venomous web-building spider of northeastern North America known for its glossy black body and often red hourglass marking. Source: https://insectscanner.com/species/northern-black-widow/ (updated 2026-10-10) ## Is it dangerous? **Venomous bite.** Bites inject neurotoxic venom that can cause latrodectism: pain spreading from the bite, sweating, nausea, muscle cramps and abdominal rigidity, sometimes with raised blood pressure. Children, older people and those with heart conditions are at higher risk. First aid: stay calm, wash the bite with soap and water, apply a cold pack, keep the limb still, and seek medical care promptly or call poison control. Go to emergency care for severe pain, cramping, breathing difficulty or chest pain. Antivenom exists but is used selectively; pain control and observation are the usual treatment. Deaths are very rare with modern care. **Pets:** Can be dangerous to pets, especially cats, which are very sensitive to widow venom; bites may cause pain, muscle tremors and rigidity, drooling, vomiting and weakness. Seek veterinary care promptly if a bite is suspected. ## Quick facts - Scientific name: Latrodectus variolus - Also called: Northern widow, Northern black-widow spider - Order: Araneae (Spiders) - Family: Theridiidae (Comb-footed spiders) - Size: Females about 8-13 mm body length; males about 3-6 mm - Colours: Glossy black, Red (hourglass marking), Brown (male) - Habitat: Undisturbed, sheltered locations near the ground: woodpiles, garages, basements, sheds, crawl spaces, hollow logs and under stones or debris. - Range: Eastern North America: southeastern Canada (southern Ontario to the Maritimes) and the eastern United States south to northern Florida and west to the Great Plains, most common in the Northeast. - Active: Most active spring through early fall; nocturnal and crepuscular (active at night and twilight). - Lifespan: Females often live 1-3 years; males typically shorter, often dying soon after mating. - Effect on plants: Harmless - Pest: no ## Overview Latrodectus variolus is a species of widow spider native to northeastern North America. Females build irregular, sticky cobwebs in sheltered, undisturbed locations near the ground and are relatively sedentary. They are best known for their potent neurotoxic venom; bites can cause systemic symptoms in people but are rarely fatal with modern medical care. Males are smaller, less venomous, and more slender than females and are often seen near webs only during mating season. ## How to identify it Adult females are about twice the size of males with a rounded, bulbous abdomen that is glossy black. Females show a red hourglass on the underside of the abdomen that is typically broken into two separate parts. There is usually a row of red spots along the top of the abdomen, often edged with white. Males are smaller, slimmer, and may be brownish or patterned with white or red markings; they lack the large spherical abdomen of females. - Glossy, rounded black abdomen on females with a red hourglass on the underside that is usually split into two parts. - Females larger and more bulbous than males; males are smaller, slimmer and more patterned. - Irregular, tangled cobwebs in sheltered, low locations like woodpiles, sheds, and basements. - A row of red spots on the top of the abdomen and a broken hourglass point to the northern black widow; a complete hourglass and no dorsal spots suggest the southern black widow. ## Lookalikes - **Southern black widow** (Latrodectus mactans): L. mactans is more common in the southeastern United States, and ranges overlap; L. mactans usually has a complete, joined hourglass and lacks the row of red spots on top of the abdomen that L. variolus usually shows. - **Western black widow** (Latrodectus hesperus): Found in western North America; similar in appearance but separated geographically. L. hesperus females often show more prominent dorsal red markings. - **False black widow** (Steatoda spp.): False widows (Steatoda) are usually brown to purplish-black with paler markings and no red hourglass; their bites are generally far less severe. ## Life cycle - **Egg:** Females produce one or more silken egg sacs, each containing dozens to hundreds of eggs, and guard or hide the sacs in the web. - **Spiderling (juvenile):** Young spiders hatch from eggs as spiderlings (juveniles) and disperse by ballooning or crawling; they molt several times as they grow. - **Adult:** Mature spiders mate (males approach female webs cautiously), then females continue to live and produce additional egg sacs; males often die shortly after mating. ## Diet and predators - Young eat: Small flying or crawling insects and other tiny arthropods caught in the web. - Adults eat: Variety of insects and other arthropods (flies, mosquitoes, beetles, ants) captured in sticky cobwebs; spiders wrap prey in silk and inject digestive enzymes. - Predators of the young: Birds, ants, predatory wasps and other spiders. - Predators of adults: Wasps (especially certain pompilid wasps), birds, lizards, and larger spiders; some parasitic wasps target egg sacs. ## Effect on plants and gardens Does not feed on plants; beneficial as a predator of insects and some pest species. ## Where and when to find it Look in undisturbed, sheltered locations near the ground: inside garages, basements, sheds, woodpiles, hollow logs, rock crevices and under debris. Check clothing, shoes and gloves stored in these areas before putting them on. - Best time: Spring through early fall; nocturnal and most active at night and twilight. - Tips: Wear gloves when cleaning cluttered areas, use a flashlight to inspect dark corners, and photograph from a safe distance rather than handling. To confirm ID, a clear photo of the underside showing the hourglass helps. ## Fun facts - The name 'widow' comes from early observations that females sometimes eat the males after mating, though this is not common for every mating. - Latrodectus variolus females can survive and reproduce for more than a year, producing multiple egg sacs in a season. - Their irregular cobwebs are built close to the ground and are highly effective at catching crawling as well as flying prey. ## Frequently asked questions ### Are northern black widows dangerous? Yes, they can be — they are venomous and can cause significant symptoms in humans, but bites are rarely fatal with prompt medical care. ### Do northern black widows bite people? They bite defensively if disturbed or trapped against the skin. Most bites occur when people put on shoes, gloves, or grab wood/objects hiding a spider. ### Why is there a black widow in my house? They seek quiet, sheltered, cluttered places with insects to eat — basements, garages, attics, sheds, and woodpiles are common indoor or near-house sites. ### How do I get rid of black widows? Reduce clutter and seal entry points, remove wood/debris from near foundations, keep storage off the floor, clean webs with a broom or vacuum, and use gloves when handling stored items. For heavy infestations, consider a licensed pest professional. Take care to avoid being bitten when removing spiders or nests. ### What should I do if I'm bitten? Remain calm, wash the bite with soap and water, apply a cold pack for pain control, immobilize the affected limb, and seek medical attention promptly. Children, elderly people, and those with medical conditions should get urgent care. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/146706), [Wikipedia](https://en.wikipedia.org/wiki/Latrodectus_variolus). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.