Black Widow Spider

Common Name - Black Widow Spider

Category - Spiders & Relatives

ScientificName - Latrodectus mactans

Kingdom - Animalia

Phylum - Arthropoda

Class - Arachnida

Order - Araneae

Family - Theridiidae

Genus - Latrodectus

Species - mactans


Description - Medium-sized, shiny black spiders with large, spherical abdomens; usually with one or more red markings on the abdomen, especially on the underside

Size - Females 12 – 16 mm long, males 5 – 10 mm long

Ecological Role - Black widow spiders are predators of many insect species, especially small, soft-bodied flying insects that are easily captured in the widow's web. When a small creature becomes entangled in her web, a black widow quickly bites the prey, injecting it with a paralyzing nerve poison. The spider then wraps the prey in silk to further immobilize it. The spider will then eat the victim, or save it for a later feeding.

Black widow spiders are part of the "cobweb spider" family, Theridiidae. Like most cobweb spiders, black widows build a compact, tangled web, usually in a sheltered location. Although many spiders are able to chew solid food, cobweb spiders like the black widow feed only on the fluids inside their prey. Although black widows are predators, they are sometimes eaten by birds and other spiders.

Fun Facts - Female black widows have a reputation for eating male black widows – hence the name "widow." This reputation is exaggerated; although females sometimes eat males, this does not always occur. A female does not always try to eat the male, and if she does, the male is often able to escape.

Male black widow spiders are not known to bite humans.

The bite from a female black widow is seldom life threatening, but medical help should be sought immediately. An antivenin for black widow bites has been developed. For more information about the medical significance of the black widow, see the Related Sites section of this account.

The black widow spider is one of the few shiny black spiders that live in Kentucky. There are a few species of shiny black cobweb spiders that resemble the black widow, but these are much smaller (less than 5 mm), and lack red markings.

Food - Small flying insects, including moths, flies, aphids, and wasps





Habitat - Most outdoor environments, including urban, rural, and forested areas; usually makes a web a few feet from the ground in thick brambles, hollow logs, rock piles or other sheltered areas

Kentucky Distribution - Statewide

Life Cycle - Like all spiders, black widows have incomplete metamorphosis, with egg, nymph, and adult stages; spider nymphs are usually called "spiderlings;" adult female black widows lay hundreds of eggs at once, and these eggs are wrapped in a protective silken egg sac; upon hatching the tiny (2 mm) spiderlings begin hunting for tiny flies, aphids, and other creatures; spiderlings molt (shed their skins) numerous times as they grow into adults; upon reaching adulthood, female black widow spiders can live for up to 3 years; adult male black widows are much smaller than females, and typically live for less than 1 year

Life Span

Life Stage


Seasonal Changes


Status - Abundant




What We Can Do - Although black widow spiders can be dangerous to humans, they are also an important part of our ecosystem, and should not be killed when they are encountered. Plus, black widow spiders will only bite humans if they are grabbed or if their web is disturbed: since black widow spiders usually build their webs in out-of-the-way places (not in the middle of a trail, for instance) they are rarely a threat to people. Learn to recognize and avoid the black widow spider instead of killing it.


Diagnosis and Control

Interesting Facts

Contributed By

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