Black Widow Spider
Latrodectus varians / Latrodectus mactans
Theridiidae (Cobweb Spiders), Order Araneae. Key family characteristics include a rounded abdomen, comb-like serrated bristles on the hind tarsi used to pull silk over prey, and generally building irregular, tangled three-dimensional webs.
Physical Description
The spider has a compact, glossy cephalothorax and a distinctly globular, bulbous abdomen. Females are much larger than males with prominent rounded abdomens. The texture appears smooth and shiny, characteristic of widow spiders.
Size Estimate
Body length is roughly 8 to 13 millimeters for females, with a leg span reaching up to 38 to 50 millimeters. This specimen appears to be an adult female.
Coloration & Markings
Deep, glossy jet black overall coloration with a striking reddish marking visible on the dorsal or ventral side of the abdomen. Juveniles and some adult females may exhibit subtle red, white, or yellowish lateral stripes or spots.
Web Type
Irregular, sticky cobweb or tangle web constructed close to the ground in dark, sheltered, undisturbed locations. The web consists of a dense scaffolding of strong silk threads with sticky vertical catch lines.
Eye Arrangement
Eight small, dark eyes arranged in two distinct transverse rows of four, set on the anterior portion of the cephalothorax.
Leg Characteristics
Long, slender, smooth black legs lacking heavy spination, featuring a specialized comb-like row of bristles on the fourth pair of legs used for wrapping prey.
Venom & Safety Information
Venom Information
Neurotoxic venom containing latrotoxin, which affects the nervous system. The venom is potent, but because the spider injects a very small quantity, bites are rarely fatal to healthy adults.
Medical Significance
Medically significant. A bite can cause severe local pain followed by painful muscle cramping, abdominal rigidity, nausea, sweating, and restlessness. Medical attention should be sought promptly if bitten.
Safety Recommendations
Wear gloves when moving firewood or cleaning out dark corners. If found indoors, relocate the spider outdoors using a container and a piece of card, or contact pest control if the infestation is large.
Habitat & Behavior
Habitat & Range
Found globally in temperate and tropical regions. Prefers dark, dry, protected microhabitats such as woodpiles, rock crevices, under structures, crawl spaces, and undisturbed corners of sheds or garages.
Behavior & Temperament
Timid and non-aggressive. They typically retreat when disturbed and only bite defensively when trapped, squeezed, or accidentally pressed against human skin.
Diet & Prey
Insects including flies, mosquitoes, grasshoppers, beetles, and caterpillars, as well as other spiders. Prey is captured in the sticky tangle web, immobilized with venom, and wrapped in silk.
Seasonal Activity
Most active during the warm spring, summer, and early autumn months. Mating typically occurs in spring, and females overwinter in sheltered locations.
Description
The Black Widow is one of the most iconic and easily recognizable spiders due to its glossy black body and warning coloration. While famous for its potent neurotoxin, it is a shy creature that prefers to avoid human contact entirely.
Key Features
Glossy black, bulbous abdomen, often accompanied by a red marking, combined with an irregular tangle web and long, slender black legs.
Similar Species
False widow spiders (Steatoda species), which lack the distinct hourglass or bright red markings and typically have broader, less globular abdomens.
Life Cycle
Females construct pear-shaped silk egg sacs containing hundreds of eggs. Spiderlings disperse via ballooning. Females can live for up to three years, while males have a much shorter lifespan.
Ecological Importance
Acts as an effective natural predator of insect populations, helping control pest species in its natural and domestic habitat.
Conservation Status
Not evaluated by the IUCN, but populations are secure and widespread, frequently adapting well to human-altered environments.
Interesting Facts
Female black widows rarely engage in sexual cannibalism as often popularized, though it does occasionally occur. Their silk is among the strongest and most elastic biological materials known.
Photography Tips
Maintain a safe distance and use a macro lens. Ensure good lighting to highlight the glossy texture and any red markings without disturbing the spider.
Identified: 2026-07-31T22:08:09.457905