Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Key family characteristics include a generally globular abdomen in females, comb-like serrated bristles on the fourth tarsus used for flinging silk over prey, and building irregular tangle webs.
Physical Description
The spider exhibits a bulbous, swollen, nearly spherical abdomen and a smaller, elongated cephalothorax. Females are notably larger with a distinctly rounded, high-domed abdomen. The body is covered in fine setae and has a mottled, textured appearance characteristic of cobweb spiders.
Size Estimate
Body length ranges from 5 to 8 millimeters for females and 3.8 to 4.7 millimeters for males, with a leg span of roughly 2 to 3 centimeters. This specimen appears to be an adult female based on the robust, globular abdomen.
Coloration & Markings
Coloration varies widely from yellowish-brown to dark brown or nearly black. The abdomen typically features distinct darker chevrons, spots, or angular markings along the dorsal midline, sometimes bordered with white or lighter tones.
Web Type
Builds an irregular three-dimensional tangle web, commonly known as a cobweb. These webs are constructed in dark corners, under furniture, near windows, or in sheltered outdoor structures, consisting of sticky silk threads running in all directions.
Eye Arrangement
Eight small eyes arranged in two rows of four, typical of the Theridiidae family. The lateral eyes are often touching or closely situated, while the median eyes are positioned in a distinct rectangular or trapezoidal area.
Leg Characteristics
The legs are moderately long, slender, and distinctly banded with dark and light rings. They feature fine spines and hairs, and the hind legs possess a specialized comb of serrated bristles used to wrap captured prey in silk.
Venom & Safety Information
Venom Information
Neurotoxic venom designed specifically for immobilizing small invertebrate prey. While capable of delivering a defensive bite if trapped directly against human skin, the venom has very low potency in humans.
Medical Significance
Not medically significant. Bites are rare, usually occurring only when accidentally squished against the skin. Symptoms are generally mild, limited to localized pain, minor redness, and slight swelling that resolves quickly without medical intervention.
Safety Recommendations
No special precautions needed. If removal is desired, gently guide the spider into a cup using a piece of card and release it outdoors. Keep living spaces tidy to minimize insect prey that attracts them.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution, found worldwide in temperate and tropical regions. Prefers anthropogenic habitats such as houses, barns, sheds, basements, and garages, as well as sheltered natural locations like rock overhangs and hollow trees.
Behavior & Temperament
Timid and non-aggressive. Spiders hang upside down in their webs waiting for prey. When disturbed, they typically drop from the web on a silken thread, retreat to a nearby crevice, or play dead.
Diet & Prey
Generalist predator feeding on a wide variety of household and garden insects including flies, mosquitoes, ants, beetles, moths, and occasionally other spiders. Prey is subdued using sticky silk and potent venom before being consumed.
Seasonal Activity
Active year-round indoors, though reproduction and peak visibility of mature specimens typically occur during the warmer spring and summer months.
Description
The Common House Spider is a familiar and harmless resident of homes and outbuildings across the globe. Recognized by its bulbous, patterned abdomen and messy corner webs, this skilled predator quietly patrols human dwellings, consuming countless nuisance insects. Though unassuming, it is an ecologically successful species perfectly adapted to living alongside humans.
Key Features
Rounded, globular abdomen; mottled brown or grey coloration with chevron markings; irregular cobweb construction in corners; presence of a serrated comb on the hind tarsi.
Similar Species
Steatoda grossa (False Black Widow) has a darker, shinier, more purplish-black or reddish-brown body with lighter crescent markings, and Loxosceles reclusa (Brown Recluse) features a violin-shaped marking on the cephalothorax and lacks patterned chevrons on the abdomen.
Life Cycle
Females construct brownish, pear-shaped papery egg sacs containing up to several hundred eggs, hanging them within the web. Spiderlings disperse via ballooning after hatching. They undergo multiple molts to reach maturity, with a total lifespan typically ranging from one to several years.
Ecological Importance
Serves as an effective natural pest control agent inside buildings and gardens by preying on disease-vector insects like mosquitoes and flies, while also forming an important link in the urban and suburban food web.
Conservation Status
Not evaluated by the IUCN, but populations are extremely secure, widespread, and thriving globally in association with human habitations.
Interesting Facts
Females can produce multiple egg sacs over a single mating season from just one mating event. They often maintain the same web location for months or even years, adding new silk scaffolding over old debris.
Photography Tips
Use macro lenses or a smartphone with macro capabilities. Photograph from the side or top down to capture the full abdominal pattern. Ensure adequate, even lighting and maintain a steady hand as the spider may freeze or drop when approached.
User Notes
Identified: 2026-10-05T22:11:27.177847