Western Black Widow
Latrodectus hesperus (likely, based on context and appearance)
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
A medium-sized spider with a robust, bulbous abdomen and a smaller cephalothorax. The legs are slender, and the body surface is typically glossy and smooth.
Size Estimate
Body length approximately 8-15mm for adult females; leg span 25-35mm. The specimen in the image appears to be a sub-adult or adult female.
Coloration & Markings
Typically jet black with a red hourglass on the underside. This specific specimen appears brownish or mottled, which is common in juveniles or sub-adults, where they retain tan, orange, or white patterns on the dorsal side of the abdomen.
Web Type
Tangle web (cobweb). A messy, three-dimensional lattice of very strong, sticky silk, often built in corners or under ledges.
Eye Arrangement
8 eyes in two rows of four; typical of Theridiids, the eyes are small and not a primary diagnostic feature for field identification relative to the web and body shape.
Leg Characteristics
Long, spindly legs; the first and fourth pairs are noticeably longer than the middle pairs. They lack heavy spines, appearing smooth and tapered.
Venom & Safety Information
Venom Information
Neurotoxic venom containing alpha-latrotoxin. It is highly potent but delivered in very small quantities.
Medical Significance
Medically significant. Bites cause latrodectism, characterized by severe muscle pain, cramping, and sweating. While rarely fatal for healthy adults, medical attention is recommended for children or the elderly.
Safety Recommendations
Wear gloves when reaching into dark corners or moving wood. If found, relocate using a jar and stiff paper. Do not handle with bare hands.
Habitat & Behavior
Habitat & Range
Common across Western North America. They prefer dark, undisturbed microhabitats like woodpiles, eaves, crawl spaces, and under outdoor furniture.
Behavior & Temperament
Reclusive and non-aggressive. They spend most of their time hanging upside down in the web. They only bite when pressed against skin or if their web is directly disturbed near the spider.
Diet & Prey
Generalist predators feeding on various insects, woodlice, and other spiders. They use their strong silk to wrap prey before delivering a bite.
Seasonal Activity
Active year-round in warmer climates, but most sightings occur in late summer and autumn during mating season.
Description
A characteristic cobweb weaver often found near human structures. Its messy web of exceptionally strong silk is a tell-tale sign of its presence.
Key Features
Glossy body, bulbous abdomen, messy tangle web with high-tensile silk, and the diagnostic red hourglass (on the ventral side).
Similar Species
Steatoda grossa (False Black Widow) which lacks the red hourglass and has less potent venom. Brown Widows (L. geometricus) have spiked egg sacs.
Life Cycle
Females produce papery, tan egg sacs containing hundreds of eggs. Spiderlings disperse via ballooning. Females can live for 1-3 years.
Ecological Importance
Vital for controlling populations of garden pests and nuisance insects like flies and crickets.
Conservation Status
Not evaluated by IUCN, but populations are stable and abundant in suburban environments.
Interesting Facts
Widow silk is one of the strongest natural fibers known, with a tensile strength comparable to high-grade alloy steel.
Photography Tips
Focus on the underside to capture the hourglass if possible. Use a flashlight to highlight the silk structure and the spider against the dark background.
Identified: 2026-07-09T01:24:56.685637