Giant House Spider
Eratigena atrica
Agelenidae (Funnel-web weavers), Order Araneae. Key family characteristics include three pairs of spinnerets with the posterior pair notably elongated, and an agile running ability.
Physical Description
Robust body with a brown cephalothorax featuring darker lateral stripes, and an elongated oval abdomen that is finely haired and slightly plump, typical of mature females.
Size Estimate
Body length is approximately 12-18 mm for females, with a leg span reaching up to 60-100 mm, making it one of the largest spiders found inside homes in its range.
Coloration & Markings
Mottled brown, beige, and yellowish-grey coloration. The abdomen features a distinct speckled or chevron-like pattern, while the cephalothorax has longitudinal dark bands.
Web Type
Messy sheet web with a distinct funnel-shaped retreat at one end, constructed in dark, undisturbed corners, behind furniture, or in cellars and sheds.
Eye Arrangement
Eight eyes arranged in two slightly curved, roughly parallel horizontal rows of four, all relatively uniform in size.
Leg Characteristics
Long, robust legs covered with visible hairs and spines, lacking pronounced banding, held spread out widely to detect vibrations on the sheet web.
Venom & Safety Information
Venom Information
Neurotoxic venom primarily targeted at insect prey. It is low in potency regarding humans and is not considered medically significant.
Medical Significance
Harmless to humans. Bites are extremely rare, usually occurring only when trapped against human skin. Symptoms are mild and generally limited to localized minor pain or redness.
Safety Recommendations
Keep living spaces tidy and seal entry points if desired. If relocation is necessary, place a container over the spider and slide a piece of paper underneath.
Habitat & Behavior
Habitat & Range
Native to Europe and introduced to parts of North America and Central Asia. Prefers damp, cool microhabitats, frequently found in human structures, basements, sheds, and woodpiles.
Behavior & Temperament
Non-aggressive and timid. It flees rapidly when disturbed, though females guarding egg sacs may stand their ground. They are primarily nocturnal hunters.
Diet & Prey
Generalist predators feeding on various household insects, including flies, silverfish, cockroaches, and other spiders, subdued quickly within their funnel webs.
Seasonal Activity
Most commonly seen in late summer and autumn, which coincides with the mature males actively wandering in search of females.
Description
The giant house spider is an impressive yet harmless arachnid frequently encountered in human dwellings during late summer and autumn. With its large leg span and rapid movements, it often startles homeowners, but it plays a beneficial role by regulating household insect populations.
Key Features
Large size, mottled brown and grey body, long hairy legs, 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 potentially Loxosceles reclusa (Brown Recluse), which lacks the hairy legs and patterned abdomen.
Life Cycle
Females construct silken egg sacs in autumn, containing dozens of eggs. Spiderlings hatch in spring, undergoing multiple molts to reach maturity with a lifespan of up to 2-3 years.
Ecological Importance
Acts as an effective natural pest controller in homes and outbuildings, helping to suppress populations of nuisance insects.
Conservation Status
Not evaluated by the IUCN, but populations are secure, abundant, and widely distributed across its native and introduced ranges.
Interesting Facts
Despite their intimidating appearance and speed, giant house spiders are exceptionally poor climbers on smooth vertical surfaces like bathtubs.
Photography Tips
Photograph from a side angle with natural lighting or a soft flash to capture the detailed abdominal patterns and leg texture without causing the spider to flee into its retreat.
Identified: 2026-09-30T15:46:30.263933