Giant House Spider
Eratigena atrica
Agelenidae (Funnel-web weavers), Order Araneae. Key family characteristics include rapid movement, a distinctive funnel-shaped retreat web, and elongated posterior spinnerets.
Physical Description
Robust, elongated body with a distinctly patterned cephalothorax and a velvety, hairy abdomen. The body is covered in fine setae. Females are generally larger and bulkier than males, while mature males possess enlarged pedipalps used in reproduction.
Size Estimate
Body length ranges from 10 to 18 mm for females and slightly smaller for males, with a total leg span reaching up to 75 to 100 mm. This specimen appears to be an adult.
Coloration & Markings
Mottled brown, dirty yellow, and grey coloration. The carapace features distinctive lighter yellowish markings, often described as a chevron or dagger pattern pointing forward, while the abdomen shows a complex, mottled herringbone or chevron pattern.
Web Type
Builds a flat, dense sheet web with a tubular retreat at one end (funnel web). The web is typically constructed in dark, undisturbed corners near ground level, such as behind furniture, in basements, or sheds.
Eye Arrangement
Eight small eyes of roughly equal size arranged in two slightly curved, horizontal rows of four across the front of the carapace.
Leg Characteristics
Long, robust, tapering legs covered in fine hairs and visible spines. The legs are typically splayed wide to maximize tactile sensation on the web sheet. No specialized structures like calamistrum are present.
Venom & Safety Information
Venom Information
Neurotoxic venom primarily adapted for immobilizing small invertebrate prey. While capable of piercing human skin, the venom is of very low potency to humans.
Medical Significance
Not medically significant. Bites are extremely rare, usually only occurring if the spider is directly pressed against bare skin. Symptoms are typically mild and localized, resembling a minor bee sting with temporary redness and swelling.
Safety Recommendations
Avoid handling them bare-handed to prevent accidental bites. If relocation is necessary, gently place a cup over the spider, slide a piece of paper underneath, and release it outdoors.
Habitat & Behavior
Habitat & Range
Native to Europe and introduced to parts of North America (particularly the Pacific Northwest) and Central Asia. Prefers dark, humid, and sheltered microhabitats such as cellars, crawl spaces, hollow logs, and rock piles.
Behavior & Temperament
Timid and fast-moving. They spend most of their time hidden inside their funnel retreat, rushing out only when vibrations signal prey trapped on the sheet web. They are non-aggressive and will flee rather than bite when disturbed.
Diet & Prey
Generalist predators feeding on various ground-dwelling insects, including cockroaches, beetles, flies, and other spiders. Prey is subdued with venom injected through chelicerae after being rushed on the web.
Seasonal Activity
Most commonly seen in late summer and autumn (specifically September and October) when mature males leave their webs to wander in search of females.
Description
The Giant House Spider is one of the largest common household spiders. Known for its impressive leg span and incredible running speed, it commands attention when encountered indoors. Despite its intimidating size, it is a largely beneficial and docile resident of dark corners.
Key Features
Large size, long hairy legs, distinctive mottled brown and yellowish-grey herringbone patterns on the abdomen, and construction of a flat sheet web ending in a tubular retreat.
Similar Species
Tegenaria domestica (Barn Funnel Weaver) which is generally smaller and more distinctly banded, and Eratigena agrestis (Hobo Spider) which lacks distinct dark banding on the legs and requires microscopic examination for definitive separation.
Life Cycle
Females construct silk egg sacs in autumn, hiding them near the retreat. Spiderlings hatch in spring and disperse. They can live up to 2 to 3 years, molting multiple times before reaching maturity.
Ecological Importance
Acts as an effective natural pest control agent in homes and outbuildings by keeping populations of crawling insects and other arthropods in check.
Conservation Status
Not evaluated by the IUCN, but populations are secure, abundant, and expanding in introduced regions.
Interesting Facts
Giant house spiders were once recognized in the Guinness Book of World Records as one of the fastest running spiders, capable of speeds up to 0.5 meters per second.
Photography Tips
Use natural lighting or an external diffuser to capture the fine setae and abdominal patterns without harsh glare. Maintain a safe macro distance and photograph from above to clearly show carapace markings.
Identified: 2026-08-25T18:50:02.752797