Common House Spider, American House Spider
Parasteatoda tepidariorum
Theridiidae (Cobweb Spiders), Order Araneae
Physical Description
Bulbous, globular abdomen with a pear-shaped body, featuring a smaller cephalothorax. Females are typically larger and rounder, while males are slimmer with longer legs and distinct palps.
Size Estimate
Body length ranges from 3 to 8 mm for females and slightly smaller for males, with a leg span up to 2.5 cm.
Coloration & Markings
Varied mottled brown, tan, and grayish coloration with chevron or triangular patterns along the top of the abdomen, sometimes featuring dark or light spots.
Web Type
Irregular tangle web (cobweb) constructed in corners of ceilings, walls, dark recesses, and protected outdoor areas.
Eye Arrangement
Eight small eyes arranged in two parallel rows of four, typical of the Theridiidae family.
Leg Characteristics
Long, slender legs with faint darker banding, lacking heavy spination, often held loosely in the three-dimensional web.
Venom & Safety Information
Venom Information
Neurotoxic venom geared towards small insect prey; generally ineffective and harmless to humans.
Medical Significance
Not medically significant. Bites are extremely rare, non-toxic to humans, and produce only minor localized redness or mild discomfort if they occur.
Safety Recommendations
No special safety measures required. Can be gently relocated outside using a container and a piece of paper if found in an unwanted location.
Habitat & Behavior
Habitat & Range
Cosmopolitan distribution; highly synanthropic, frequently found inside human dwellings, barns, garages, and sheltered outdoor structures.
Behavior & Temperament
Docile, sedentary web-weaver that remains in or near its retreat day and night, retreating when disturbed.
Diet & Prey
Insects including flies, mosquitoes, ants, beetles, and occasionally other spiders caught in its sticky web.
Seasonal Activity
Active year-round indoors due to climate control, with increased wandering and mating activity during warmer spring and autumn months.
Description
The Common House Spider is a familiar and harmless indoor roommate, frequently found hanging upside down in untidy webs in room corners. As an expert insect hunter, it quietly helps control household pests.
Key Features
Globular, bulbous abdomen with chevron markings, paired with a tangle web constructed high in corners or near ceilings.
Similar Species
Steatoda species (False Widows), which have a glossier, more uniform dark or reddish-brown body compared to the patterned Parasteatoda tepidariorum.
Life Cycle
Females produce brownish, pear-shaped papery egg sacs containing hundreds of eggs. Spiderlings disperse via ballooning after hatching; lifespan can exceed one year.
Ecological Importance
Serves as an effective natural pest controller in domestic environments by intercepting flying and crawling insects.
Conservation Status
Not evaluated by the IUCN; highly secure and thriving globally due to its close association with human habitats.
Interesting Facts
Females can produce up to 17 egg sacs in their lifetime, containing a total of several thousand eggs, and often live for more than a year in human homes.
Photography Tips
Use macro lenses or smartphone macro settings with good lighting. Photograph from the side or underneath the web to capture dorsal abdominal markings clearly.
User Notes
On the ceiling
Identified: 2026-08-25T08:02:12.196400