Western Black Widow (immature or male specimen)
Latrodectus hesperus
Family Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The specimen displays a bulbous, slightly elongated abdomen and a smaller cephalothorax. Based on the orange-brown coloration and distinct white-bordered markings, this is an immature female or a male. Adult females are famously glossy black.
Size Estimate
Body length 4–10mm; leg span approximately 15–25mm. Likely an immature female or adult male based on the striped pattern.
Coloration & Markings
Tan to orange-brown base color. The dorsal side of the abdomen features a central row of white and orange spots or 'chevrons' with dark borders. Adult females lose these and turn jet black with a red hourglass underside.
Web Type
Tangle web or 'cobweb'. A messy, three-dimensional structure of exceptionally strong, irregular silk lines, usually near the ground or in dark corners.
Eye Arrangement
Eight eyes in two horizontal rows typical of Theridiidae; they are small and generally difficult to see without macro photography.
Leg Characteristics
Long, slender legs. The first and fourth pairs are significantly longer than the middle pairs. They lack heavy spines but have small 'comb-feet' on the fourth tarsi for silk manipulation.
Venom & Safety Information
Venom Information
Contains latrotoxin, a potent neurotoxin. While immature spiders and males have less venom, adult females possess venom that affects the nervous system of mammals.
Medical Significance
Medically significant. Bites from adult females cause 'latrodectism' (muscle aches, abdominal cramping, sweating). However, they are rarely fatal. Males and juveniles are considered much less dangerous due to smaller venom glands.
Safety Recommendations
Use gloves when moving woodpiles or cleaning garages. If bitten, seek medical advice, especially if symptoms like muscle pain or nausea develop. Do not handle with bare hands.
Habitat & Behavior
Habitat & Range
Common throughout Western North America, particularly abundant in California. Found in woodpiles, garages, crawl spaces, and under eaves of houses.
Behavior & Temperament
Extremely shy and reclusive. They spend most of their time in a 'retreat' in the web. They are not aggressive and usually drop from the web or play dead (thanatosis) when disturbed.
Diet & Prey
Primarily crawling insects like beetles, crickets, and sowbugs, though they can capture flying insects that stumble into the low-hanging tangle web.
Seasonal Activity
Active year-round in California, with peak visibility and mating occurring from late spring through autumn.
Description
An iconic resident of the American West, this spider represents the transition phase of the Latrodectus genus. Its intricate tan and white abdominal patterns are a beautiful contrast to the solid black of its mature form.
Key Features
Tangle web with high silk strength, tan/orange legs, and the specific white-outlined dorsal stripes on the abdomen.
Similar Species
Steatoda grossa (False Black Widow), which lacks the bright orange/red tones and the specific dorsal stripe pattern; Latrodectus geometricus (Brown Widow), which has a more geometric 'broken' pattern.
Life Cycle
Females produce tan, papery, teardrop-shaped egg sacs containing hundreds of eggs. Spiderlings emerge with the tan/striped pattern seen in the image and darken as they molt toward maturity.
Ecological Importance
Highly effective at controlling populations of garden pests and indoor nuisances like cockroaches and crickets.
Conservation Status
Not evaluated by IUCN; common and stable throughout its range.
Interesting Facts
The silk of a black widow is one of the strongest biological materials known, possessing high tensile strength comparable to high-grade steel.
Photography Tips
Focus on the dorsal abdominal pattern for age identification. Side shots can help reveal the presence of a partial hourglass on the underside.
User Notes
Found outside in Northern California near a house.
Identified: 2026-06-12T23:13:42.643745