Western Black Widow
Latrodectus hesperus
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
Compact and bulbous body shape with a globular abdomen, slender cephalothorax, and smooth, glossy exoskeleton.
Size Estimate
Body length around 8 to 15 mm for females, with a leg span of approximately 38 mm. Appears to be an adult female specimen.
Coloration & Markings
Glossy jet black base coloration with a distinctive red or orange hourglass marking on the ventral side of the abdomen, sometimes accompanied by red spots dorsally.
Web Type
Irregular tangle web (cobweb) constructed near ground level in dark, sheltered crevices.
Eye Arrangement
Eight small eyes arranged in two rows of four, typical of the Theridiidae family.
Leg Characteristics
Slender, long legs with dark coloration, lacking heavy spination but possessing a comb-like row of serrated setae on the hind tarsi for pulling silk.
Venom & Safety Information
Venom Information
Neurotoxic venom containing latrotoxin, which affects the nervous system; potent, though fatalities are extremely rare with modern medical care.
Medical Significance
Medically significant; bites cause localized pain followed by severe muscle cramps, abdominal rigidity, sweating, and nausea, requiring medical evaluation.
Safety Recommendations
Wear gloves when moving stacked wood or cleaning dark corners, avoid barefoot walking outdoors at night, and relocate spiders outdoors using a container if found inside.
Habitat & Behavior
Habitat & Range
Found across western North America, typically inhabiting dark, dry shelters such as rock piles, woodpiles, and stone walls.
Behavior & Temperament
Reclusive, non-aggressive, and timid, preferring to retreat when disturbed; bites only occur in self-defense when pressed against skin.
Diet & Prey
Feeds primarily on crawling insects including beetles, ants, flies, grasshoppers, and other spiders caught in its web.
Seasonal Activity
Most active during the warm summer and autumn months, during which mating and egg-laying peak before adults overwinter or decline.
Description
The Western Black Widow is a notoriously recognizable yet misunderstood arachnid, famous for the female's glossy black physique and vibrant red hourglass. Preferring quiet, sheltered niches like stone walls and woodpiles, this orb-weaver relative plays a vital role in controlling insect populations.
Key Features
Glossy black body combined with a bright red or orange ventral hourglass marking and an irregular cobweb structure.
Similar Species
False black widows (Steatoda grossa) and male black widows, which lack the bright hourglass and have different abdominal patterns.
Life Cycle
Females produce multiple silken egg sacs containing hundreds of eggs each; spiderlings disperse via ballooning after hatching, reaching maturity in a few months.
Ecological Importance
Serves as an effective natural predator of pest insects, helping to regulate populations of flies, beetles, and agricultural pests.
Conservation Status
Not evaluated by the IUCN, but populations are stable, widespread, and abundant across their native range.
Interesting Facts
Despite their fearsome reputation, black widows are remarkably docile and will typically feign death or retreat rather than bite when disturbed.
Photography Tips
Use a macro lens with a stable tripod or fast shutter speed, ensure adequate lighting to reveal the glossy texture, and maintain a safe distance without disturbing the spider.
Identified: 2026-09-30T21:58:47.037267