Common House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
The common house spider has a bulbous, rounded abdomen that is distinctly higher than it is wide, paired with a relatively small cephalothorax. Females are typically larger and rounder, while males possess a narrower abdomen and longer legs.
Size Estimate
Body length ranges from 5 to 8 millimeters for females and 3.8 to 6 millimeters for males, with a total leg span reaching up to 15 to 25 millimeters.
Coloration & Markings
Coloration varies widely from yellowish-brown to dark brown or greyish. The abdomen often features mottled patterns, dark chevron markings, or pale spots edged with darker borders.
Web Type
Constructs a messy, irregular tangle web commonly known as a cobweb, positioned in corners, window frames, and crevices to intercept crawling and flying insects.
Eye Arrangement
Consists of eight small eyes arranged in two horizontal rows of four, with the lateral eyes grouped closely together on each side.
Leg Characteristics
Legs are moderately long and slender, featuring faint dark banding or rings, and lack prominent spines, characteristic of many cobweb spiders.
Venom & Safety Information
Venom Information
Possesses mild neurotoxic venom designed to immobilize small insect prey; poses virtually no chemical threat to humans.
Medical Significance
Not medically significant. Bites are extremely rare, typically only occurring if the spider is trapped directly against human skin, resulting in minor local irritation similar to a mild mosquito bite.
Safety Recommendations
No specific safety precautions needed as they are harmless; can be gently relocated outside using a cup and a piece of paper if found in an undesired location.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution worldwide; commonly found indoors in human dwellings, garages, sheds, and sheltered outdoor structures like porches and eaves.
Behavior & Temperament
Timid and non-aggressive; hangs upside down in its web and retreats rapidly when disturbed, dropping to the ground or fleeing if cornered.
Diet & Prey
Feeds primarily on small household insects such as flies, mosquitoes, gnats, ants, and other small spiders caught in its web.
Seasonal Activity
Active year-round indoors due to climate-controlled environments, with mating and increased wandering occurring most frequently during the warmer spring and summer months.
Description
The common house spider is an unobtrusive and beneficial indoor resident, frequently found tucked into window frames and quiet room corners where it quietly manages household insect populations.
Key Features
Rounded, bulbous abdomen, tangled cobweb construction, brownish mottled patterns with dark chevrons, and a frequent upside-down resting posture in the web.
Similar Species
Steatoda species (False Black Widows), which generally have a glossier, more robust appearance and darker, more uniform coloration.
Life Cycle
Females produce several brownish, pear-shaped silk egg sacs containing up to several hundred eggs, hanging them within the web; spiderlings disperse via ballooning after hatching.
Ecological Importance
Acts as an effective natural pest control agent inside homes and outbuildings, significantly reducing populations of nuisance and disease-carrying insects.
Conservation Status
Secure and widespread globally; not evaluated by the IUCN due to its high abundance and association with human habitats.
Interesting Facts
Despite their messy webs, these spiders are meticulous cleaners, often dropping old prey husks out of the web and continually modifying their silken snare for better catches.
Photography Tips
Use macro settings with a gentle light source or flashlight to illuminate the dorsal patterns, maintaining a steady hand since web vibrations may cause the spider to retreat.
Identified: 2026-08-24T00:12:52.608094