Western Black Widow, Shoebox Spider, Hourglass Spider
Latrodectus hesperus
Family Theridiidae (Cobweb Spiders), Order Araneae. Key family characteristics include a rounded, bulbous abdomen, the presence of a comb-like row of serrated bristles on the tarsus of the fourth pair of legs used to pull silk from the spinnerets, and irregular, three-dimensional cobwebs.
Physical Description
The spider features a very glossy, jet-black, globose abdomen that is nearly spherical. The cephalothorax is much smaller, smooth, and dark brown to black. Legs are slender, long, and taper smoothly. This specimen appears to be an adult female due to the characteristic large, shiny, spherical abdomen.
Size Estimate
Body length is approximately 8 to 13 millimeters, with a total leg span ranging from 25 to 38 millimeters. This matches the typical size range for a mature female black widow.
Coloration & Markings
Deep, glossy pitch-black coloration over the entire body and legs. The dorsal side of the abdomen is uniformly dark without spots, while the ventral side typically features a characteristic red or orange hourglass-shaped marking, though it may sometimes appear as two separate spots.
Web Type
Constructs an irregular, messy, three-dimensional cobweb consisting of strong, sticky silk threads anchored near ground level in dark, undisturbed corners. The web includes a dense funnel-like retreat where the spider hides.
Eye Arrangement
Equipped with eight small eyes arranged in two transverse rows of four. The eyes are roughly equal in size, set on dark tubercles, which is typical for the Theridiidae family.
Leg Characteristics
Legs are thin, glossy black, and relatively long compared to the body. The fourth pair of legs possesses a specialized comb of serrated setae used for wrapping prey. No prominent spines or banding are present.
Venom & Safety Information
Venom Information
Possesses a potent neurotoxin containing latrotoxin, which affects the nervous system by causing massive neurotransmitter release. While medically significant, bites are rarely fatal to healthy adults with prompt medical care.
Medical Significance
Danger level is moderate to high (medically significant). Bite symptoms include immediate sharp pain, followed by severe muscle cramps, abdominal rigidity, sweating, nausea, and tremors. Medical attention should be sought immediately if bitten; antivenom and muscle relaxants are effective treatments.
Safety Recommendations
Wear heavy work gloves when moving wood, stones, or stored items in dark areas. Keep living spaces clean and clutter-free. If found indoors, gently guide the spider into a container using a long stick or broom and relocate it safely outdoors away from high-traffic zones.
Habitat & Behavior
Habitat & Range
Found widely across western North America, ranging from British Columbia through the western United States down into Mexico. Prefers dark, dry, sheltered microhabitats such as woodpiles, rock crevices, basements, crawlspaces, garages, and outdoor sheds.
Behavior & Temperament
Reclusive, non-aggressive, and strictly nocturnal. They spend nearly all their time hanging upside down in their webs. They only bite in self-defense when accidentally pressed against human skin, trapped, or when protecting an egg sac.
Diet & Prey
Feeds primarily on crawling and flying insects including flies, mosquitoes, beetles, grasshoppers, and caterpillars. Insects stumble into the sticky vertical trip-wires of the web, become entangled, and are quickly subdued by the spider.
Seasonal Activity
Most active during the warm summer and early autumn months. Mating occurs primarily in spring and summer, after which females produce multiple egg sacs before seeking sheltered spots to overwinter.
Description
The Western Black Widow is one of North America's most recognizable and misunderstood arachnids. Featuring a strikingly glossy, bulbous black body and an intensely secretive lifestyle, this spider prefers the quiet shadows of human structures or natural crevices. While its neurotoxic venom demands respect and caution, its shy demeanor means encounters rarely result in bites unless the spider is directly handled or compressed.
Key Features
Glossy jet-black spherical abdomen, slender black legs, absence of dorsal patterns, and the telltale red hourglass marking on the underside of the abdomen, combined with an irregular, sticky cobweb.
Similar Species
False black widows (Steatoda grossa) lack the glossy jet-black finish and red hourglass marking, often displaying brownish, pale geometric patterns on the abdomen. Male black widows are much smaller, lighter in color, and harmless.
Life Cycle
Females produce pear-shaped, tough silk egg sacs containing 200 to 400 eggs. Spiderlings emerge after a few weeks and disperse via ballooning on wind currents. Females live up to 1 to 3 years, while males have much shorter lifespans and frequently fall victim to sexual cannibalism after mating.
Ecological Importance
Acts as a vital apex predator within the local invertebrate food web, helping naturally regulate populations of nuisance insects and potential agricultural pests.
Conservation Status
Not evaluated by the IUCN, but populations are abundant, stable, and highly adaptable to human-altered environments.
Interesting Facts
Black widow silk is among the strongest and most elastic biological materials known, inspiring extensive scientific research. The female's notorious reputation for consuming the male after mating gave the species its famous common name.
Photography Tips
Maintain a safe distance and use a macro lens with a tripod. Use natural side lighting or a diffused flash to capture the glossy texture of the exoskeleton without creating harsh highlights. Avoid disturbing or blowing on the spider.
Identified: 2026-10-01T21:12:38.236696