Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae. Characterized by a comb-like row of bristles on the fourth leg tarsus.
Physical Description
Small spider with a bulbous, teardrop-shaped abdomen and a smaller cephalothorax. The abdomen is typically high and rounded, often appearing larger than the front section of the body.
Size Estimate
Body length 4–6 mm for females, smaller for males. Total leg span typically under 25 mm. This specimen appears to be an adult or sub-adult.
Coloration & Markings
Drab coloration ranging from tan to gray and black. Abdomen often features a mottled pattern of chevrons and spots, typically with dark patches and lighter streaks. Males are generally darker and more slender.
Web Type
Tangle web or cobweb. A messy, three-dimensional structure of crisscrossing silk, usually built in corners or under ledges, often with a central retreat area.
Eye Arrangement
Eight eyes in two rows of four. The eyes are small and lack the high magnification found in hunting spiders, as they rely on web vibrations.
Leg Characteristics
Relatively long and thin legs. In females, the legs are often banded with alternating light and dark colors. The fourth pair of legs features specialized serrated bristles (the comb).
Venom & Safety Information
Venom Information
Neurotoxic venom specialized for paralyzing small insects. It is not considered hazardous to humans or large pets.
Medical Significance
Low medical significance. Bites are extremely rare and typically occur only if the spider is pressed against the skin. Symptoms are usually limited to mild localized swelling or redness.
Safety Recommendations
Harmless to humans; no intervention is usually necessary. To relocate, use a cup and a piece of paper to catch the spider and move it to a garden or shed.
Habitat & Behavior
Habitat & Range
Found globally; extremely common in North America. Primarily thrives in man-made structures: eaves, closets, basements, sheds, and window frames.
Behavior & Temperament
Extremely sedentary and non-aggressive. They spend most of their time hanging upside down in their webs. If disturbed, they usually drop to the floor or retreat rapidly.
Diet & Prey
Generalist predators consuming flies, mosquitoes, ants, moths, and even other spiders. They use sticky 'gum-foot' threads to snag crawling insects.
Seasonal Activity
Active year-round in temperature-controlled indoor environments. In outdoor settings, activity peaks in late summer and autumn.
Description
The quintessential 'house spider,' this species is the most frequent producer of cobwebs in homes. It is a master of corners, waiting patiently for household pests to stumble into its labyrinth of silk.
Key Features
Bulbous abdomen, tan/gray mottled pattern, messy cobweb, and the presence of serrated bristles on the hind legs.
Similar Species
Often confused with the Steatoda genus (False Widows), which are larger and glossier, or the Brown Recluse, which lacks the patterned abdomen and web type.
Life Cycle
Females produce distinctive pear-shaped, tan silken egg sacs. A single female can produce several sacs a year, each containing hundreds of eggs. Spiderlings disperse via ballooning.
Ecological Importance
Highly beneficial for indoor pest control, significantly reducing populations of flies, gnats, and disease-carrying mosquitoes without the use of chemicals.
Conservation Status
Not evaluated by IUCN, but extremely abundant and widespread across its range.
Interesting Facts
Despite their small size, they can successfully hunt prey much larger than themselves, including large crickets and even small lizards, by using their comb-feet to throw silk.
Photography Tips
Focus on the abdomen pattern and the web structure. Use a macro lens if possible, as their small size makes it difficult for standard phone cameras to capture eye patterns.
Identified: 2026-06-15T01:38:56.310825