Brown Widow Spider, Gray Widow, Brown Button Spider, House Button Spider
Latrodectus geometricus
Family Theridiidae (Cobweb Spiders / Comb-footed Spiders), Order Araneae. Key family characteristics include a comb-like row of serrated bristles on the tarsus of the fourth leg used to pull silk from the spinnerets.
Physical Description
The spider exhibits classic theridiid proportions with a relatively small, flattened cephalothorax, slender legs, and a large, globular, spherical abdomen. Females are significantly larger than males and possess a shiny, bulbous abdomen. The surface is mostly smooth with subtle fine hairs.
Size Estimate
Body length for adult females ranges from 7 to 10 millimeters, with a leg span of approximately 22 to 38 millimeters. This specimen appears to be an adult or subadult female based on the rounded, bulbous abdomen.
Coloration & Markings
Coloration ranges from tan and light brown to dark brown or nearly black, featuring intricate geometric or mottled patterns of white, black, gray, and brown on the dorsal and lateral sides of the abdomen. The signature diagnostic feature is the bright yellowish-orange or reddish-orange hourglass marking on the ventral side of the abdomen.
Web Type
Builds a messy, irregular three-dimensional tangle web, commonly known as a cobweb, typically constructed close to the ground or in sheltered structural crevices like corners of walls, under patio furniture, or inside recess areas.
Eye Arrangement
Consists of eight small eyes arranged in two distinct transverse rows of four each, typical of the family Theridiidae, with lateral eyes often touching or closely grouped.
Leg Characteristics
The legs are long, slender, and distinctly banded with dark brown and light tan rings. They lack heavy spination but feature the characteristic comb-like serrated bristles on the hind tarsi used for manipulating silk.
Venom & Safety Information
Venom Information
Possesses a potent neurotoxic venom (latrotoxin), but typically injects a much smaller quantity compared to the black widow. The venom affects the nervous system but is generally considered significantly less potent to humans than that of Latrodectus mactans.
Medical Significance
Medically significant, but bites are rare and usually only occur when the spider is pressed directly against the skin. Symptoms can include localized pain, muscle cramps, sweating, and nausea, though severe systemic reactions are uncommon.
Safety Recommendations
Wear gloves when clearing dark, undisturbed outdoor areas. Relocate indoor spiders using a cup and card. Seek medical attention if systemic symptoms develop following a bite.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution in tropical and subtropical regions worldwide, having spread to parts of the southern United States, Australia, South Africa, and parts of Europe. Prefers dry, warm, sheltered microhabitats around human habitations, gardens, and outbuildings.
Behavior & Temperament
Timid and non-aggressive. Spiders spend the majority of their time hanging upside down in their webs. When disturbed, they typically drop to the ground and play dead or retreat hastily to a nearby hiding spot rather than biting.
Diet & Prey
Feeds primarily on crawling and flying insects, including cockroaches, beetles, flies, and other spiders, using sticky silk threads to entrap prey before delivering a paralyzing bite.
Seasonal Activity
Active year-round in warmer climates, with peak activity and mating occurring during the warm summer and autumn months.
Description
The brown widow spider is a successful and widespread synanthropic species easily recognized by its mottled brown coloration and signature orange-to-yellow ventral hourglass. While possessing neurotoxic venom, its retiring nature and low tendency to bite make it a manageable neighbor in residential environments.
Key Features
Spiky spherical egg sacs, geometric mottled dorsal patterns on the abdomen, distinctly banded legs, and a bright orange-yellow hourglass marking on the underside.
Similar Species
Latrodectus mactans (Southern Black Widow) which is solid black with a red hourglass; Steatoda grossa (False Black Widow) which lacks the distinctive hourglass and spiky egg sacs.
Life Cycle
Females produce distinctive spiky or pom-pom-like egg sacs containing hundreds of eggs. Spiderlings disperse via ballooning after hatching. They undergo multiple molts to reach maturity, with females living up to several years in favorable conditions.
Ecological Importance
Acts as an effective natural predator of household and garden insect pests, helping to regulate local insect populations.
Conservation Status
Not evaluated by the IUCN; highly adaptable, thriving, and expanding its global range.
Interesting Facts
Brown widow egg sacs are instantly recognizable by the numerous soft, spiked projections covering their surface, resembling a miniature sea urchin.
Photography Tips
Photograph from the side to capture leg banding and dorsal patterns, and gently encourage the spider to reveal its underside to capture the diagnostic hourglass marking.
Identified: 2026-08-25T14:54:25.340967