Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Characterized by building messy, three-dimensional tangle webs and having a comb-like row of bristles on their fourth pair of legs.
Physical Description
A medium-sized spider with a very bulbous, teardrop-shaped abdomen that is significantly larger than its cephalothorax. The abdomen is often pitted or slightly dimpled. Females are much larger and more robust than males, which have more slender bodies and longer legs.
Size Estimate
Females: 5–8 mm body length; Males: 4 mm. Total leg span typically ranges from 15–25 mm. This specimen appears to be an adult female.
Coloration & Markings
Displaying a mottled pattern of tan, brown, grey, and black. A characteristic dark 'V' or chevron pattern is often visible on the back of the abdomen. The legs are typically yellowish-brown with dark banding at the joints.
Web Type
Tangle web or 'cobweb'. A messy, non-sticky structural web with sticky 'gumfoot' lines anchored to the substrate to trap crawling insects. Often found in corners of buildings, windowsills, or under eaves.
Eye Arrangement
8 eyes arranged in two rows of four. The anterior median eyes are dark, while the others are light-reflecting, which is typical for the family Theridiidae.
Leg Characteristics
Long, slender legs. The fourth pair of legs possesses a 'comb' of serrated bristles used to wrap prey in silk. Often displays dark bands or rings, especially at the joints.
Venom & Safety Information
Venom Information
The venom is neurotoxic but specifically evolved for paralyzing small insects. It is not considered dangerous or highly potent to humans.
Medical Significance
Low medical significance. Bites are rare and usually only occur if the spider is squeezed. Symptoms typically involve localized pain, swelling, and redness similar to a bee sting, resolving within 24 hours.
Safety Recommendations
Harmless. If relocation is desired, use a cup and paper to move the spider outside. They are beneficial for keeping other pest populations down and do not require professional extermination.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; found throughout the world in association with human dwellings. Commonly inhabits basements, garages, sheds, and window frames.
Behavior & Temperament
Extremely shy and non-aggressive. When disturbed, they typically retreat to a corner of the web or drop to the ground on a silk line. They are passive hunters that wait for prey to become entangled in their web.
Diet & Prey
Generalist predators feeding on flies, mosquitoes, ants, beetles, and even other spiders. They can kill prey much larger than themselves by quickly throwing silk over the victim.
Seasonal Activity
Active year-round in temperature-controlled indoor environments, though peak breeding and outdoor activity occur in late summer and autumn.
Description
The Common House Spider is the most frequent architectural companion to humans. Its mottled brown appearance allows it to blend into wood and dusty corners, where it performs essential pest control by clearing homes of flies and crawling insects.
Key Features
High bulbous abdomen, mottled brown coloration, banded legs, and the classic 'cobweb' structure. The pear-shaped brown egg sacs are a definitive diagnostic sign.
Similar Species
Steatoda borealis (False Widow), which is darker and lacks the mottling; and Latrodectus (Black Widow), which has a signature hourglass and is typically shiny black without the mottling.
Life Cycle
Females produce several pear-shaped, papery, brown egg sacs throughout the year. One sac can contain 100-400 eggs. Spiderlings disperse via ballooning. Lifespan is generally about one year.
Ecological Importance
Primary natural pest control in urban environments. They significantly reduce populations of household pests like flies, gnats, and cockroaches.
Conservation Status
Not evaluated by the IUCN, but populations are stable and widespread globally due to their success in human-altered landscapes.
Interesting Facts
They are known for their 'gumfoot' lines—silk threads with sticky droplets at the bottom that snap when an insect walks over them, hoisting the victim into the air.
Photography Tips
Focus on the side profile to capture the bulbous abdomen and the banding on the legs. Use a macro lens or 'Portrait' mode to blur the background, as their webs can create visual clutter.
Identified: 2026-06-10T23:47:14.608583