Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Key family characteristics include a rounded abdomen, comb-like setae on the tarsus of the fourth leg used to pull silk from the spinnerets, and an irregular tangle web.
Physical Description
The spider has a bulbous, globular abdomen that is noticeably larger than the cephalothorax, giving it a teardrop or rounded profile. The cephalothorax is compact and brownish. The body texture appears slightly glossy with fine hairs. Females are typically larger and rounder, while males are slender with proportionately longer legs.
Size Estimate
Body length ranges from 5 to 8 mm for females and slightly smaller for males, with a leg span of approximately 15 to 25 mm. This specimen appears to be an adult or subadult.
Coloration & Markings
Base coloration varies from yellowish-brown to dark brown or grey. The abdomen features mottled patterns, often with dark chevron markings, spots, or a series of dark triangles running down the dorsal midline. Legs are yellowish or brownish with distinct dark bands.
Web Type
Builds an irregular three-dimensional tangle web, commonly known as a cobweb. These webs are constructed in corners, near ceilings, under furniture, or around exterior crevices and window frames, featuring sticky vertical lines that snare crawling and flying insects.
Eye Arrangement
Eight eyes arranged in two rows of four, typical of the Theridiidae family. The lateral eyes are often grouped in pairs close together, while the median eyes are set apart on a slight raised tubercle.
Leg Characteristics
Legs are moderately long and slender, featuring distinct dark banding or rings. The fourth pair of legs possesses a comb of serrated bristles used for wrapping prey in silk. Legs are typically held in a contracted or sprawling posture within the web.
Venom & Safety Information
Venom Information
Neurotoxic venom tailored for immobilizing small invertebrate prey. It is low in potency regarding humans and is generally not considered medically significant.
Medical Significance
Harmless to humans. Bites are extremely rare and typically only occur if the spider is squeezed or trapped directly against the skin. Symptoms from a bite are usually minor, resembling a mild bee sting with localized redness and slight swelling.
Safety Recommendations
No special safety measures are required as they are harmless. If unwanted indoors, they can easily be relocated outside using a cup and a piece of paper. Clearing webs periodically discourages establishment.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution found worldwide, closely associated with human habitations. Prefers dark, undisturbed corners of rooms, basements, garages, sheds, porches, and outbuildings, as well as sheltered outdoor niches.
Behavior & Temperament
Docile and non-aggressive. They spend most of their time stationary hanging upside down in the center of their cobwebs. When disturbed, they typically retreat to a nearby crevice or drop from the web on a silken safety line.
Diet & Prey
Feeds on a wide variety of household and garden insects, including flies, mosquitoes, ants, beetles, moths, and other spiders. Prey is captured in the sticky tangle web, bitten, envenomated, and wrapped tightly before consumption.
Seasonal Activity
Active year-round indoors in climate-controlled buildings. Outdoors, peak activity occurs during the warmer spring, summer, and autumn months, with mating and egg-laying concentrated in late summer.
Description
The Common House Spider is a familiar and harmless roommate in homes across the world. Recognized by its bulbous, patterned abdomen and untidy corner cobwebs, this species acts as a diligent natural pest controller, quietly eliminating nuisance insects without posing any threat to humans.
Key Features
Rounded, bulbous abdomen with mottled chevron markings; untidy tangle web built in structural corners; distinct dark banding on the legs; presence of a comb-like structure on the hind tarsi.
Similar Species
Steatoda grossa (False Black Widow), which is darker, glossier, and more robust with purplish-brown to black coloration and lighter crescent markings. Latrodectus species (Black Widows), which are glossy black with a distinct red hourglass marking.
Life Cycle
Females produce brownish, pear-shaped or globular silken egg sacs containing up to several hundred eggs, which are hung within the web. Spiderlings hatch and disperse via ballooning or crawling. Females can live for more than a year, producing multiple egg sacs.
Ecological Importance
Serves as an effective natural biological control agent by reducing populations of household pests, flies, and mosquitoes. Forms an important part of the indoor and peridomestic food web.
Conservation Status
Not evaluated by the IUCN, but populations are secure, abundant, and cosmopolitan due to their close association with human habitats.
Interesting Facts
Despite their messy webs, these spiders are meticulous cleaners of their own webs, often eating and rebuilding sections. They can successfully capture prey much larger than themselves, including large beetles and stinging insects.
Photography Tips
Use macro photography with natural lighting or an external flash diffuser to highlight the abdominal patterns and leg banding. Take photos from the side or slightly above while avoiding disturbing the spider to capture its natural resting posture.
Identified: 2026-08-11T01:25:23.350527