Giant House Spider
Eratigena atrica
Agelenidae (Funnel-web weavers), Order Araneae
Physical Description
Large, robust body with a distinctively elongated, hairy abdomen and a broad cephalothorax. The body is covered in fine setae, giving it a somewhat velvety or matte texture. Females tend to have larger, heavier abdomens, while mature males possess noticeably longer legs and swollen pedipalps used in reproduction.
Size Estimate
Body length ranges from 10 to 18 mm for females and slightly smaller for males, with an impressive leg span that can reach up to 75 to 100 mm. This specimen is an adult, displaying the full robust proportions characteristic of the species.
Coloration & Markings
Muted earth tones featuring a mix of brown, yellowish-brown, and muddy grey. The cephalothorax typically exhibits indistinct darker markings, while the abdomen displays a subtle, broken herringbone or chevron pattern running down the dorsal side, interspersed with pale spots.
Web Type
Constructs a characteristic dense, flat sheet web that terminates in a tubular retreat where the spider hides, waiting for prey. These webs are typically built in dark, undisturbed corners, behind furniture, in sheds, or in woodpiles.
Eye Arrangement
Eight small, dark eyes arranged in two slightly curved, horizontal rows of four across the anterior portion of the cephalothorax, typical of the funnel-weaver family.
Leg Characteristics
Long, robust, and tapering legs covered in visible spines and fine hairs, which aid in detecting vibrations. The legs are typically uniform brown without distinct banding, held spread wide in a sprawling posture.
Venom & Safety Information
Venom Information
Contains a mild neurotoxic venom used primarily to immobilize insect prey. The venom is generally considered not medically significant to humans.
Medical Significance
Harmless to humans. While large specimens possess chelicerae strong enough to occasionally break human skin, a bite usually results in only mild, temporary localized pain or redness similar to a bee sting, with no systemic effects.
Safety Recommendations
Avoid handling them bare-handed to prevent accidental defensive bites. If found indoors, they can be easily safely relocated outside using a container and a piece of card.
Habitat & Behavior
Habitat & Range
Native to Europe and introduced to parts of North America (particularly the Pacific Northwest). Prefers dark, cool, sheltered microhabitats such as basements, garages, hollow logs, stone walls, and woodpiles.
Behavior & Temperament
Reclusive, fast-running ambush hunter that spends most of its time in or near its funnel retreat. While capable of sudden bursts of surprising speed, they are generally docile and will attempt to flee rather than bite when disturbed.
Diet & Prey
Invertebrate generalist feeding primarily on crawling and flying insects such as flies, beetles, woodlice, cockroaches, and other spiders that wander onto its sheet web.
Seasonal Activity
Most commonly seen in late summer and autumn (especially September and October) when mature males actively leave their webs in search of females during the mating season.
Description
The giant house spider is one of the largest common household spiders, known for its formidable appearance and impressive leg span. Despite its startling size and rapid movements, it is a largely harmless and beneficial occupant of dark corners, cellars, and outbuildings, where it silently helps control insect populations.
Key Features
Large size, long hairy legs without distinct banding, dull brown coloration with a subtle chevron pattern on the abdomen, and association with a flat sheet web ending in a funnel-shaped retreat.
Similar Species
Tegenaria domestica (Barn Funnel Weaver) which is generally smaller and more distinctly banded; native Hobo Spider (Eratigena agrestis), though distinguishing requires close microscopic examination of genital structures.
Life Cycle
Females produce disc-shaped egg sacs in the autumn, guarding them through the winter. Spiderlings emerge in spring, undergoing multiple molts to reach maturity within one to two years. Total lifespan can reach up to three years.
Ecological Importance
Acts as an effective apex predator among household and outbuilding invertebrates, helping to regulate populations of nuisance pests and other arthropods.
Conservation Status
Not evaluated by the IUCN, but populations are secure, abundant, and widely distributed across their native and introduced ranges.
Interesting Facts
Despite their intimidating appearance and speed (they have been recorded running up to half a meter per second), giant house spiders are poor climbers on smooth vertical surfaces like glass bathtubs.
Photography Tips
Photograph from a low angle to capture the full leg span and posture. Use natural indirect lighting or a diffused flash to highlight the subtle abdominal patterns without creating harsh shadows.
Identified: 2026-08-23T10:59:32.547690