Giant House Spider
Eratigena atrica
Agelenidae (Funnel-Weavers), Order Araneae. Key family characteristics include three pairs of spinnerets with the posterior pair notably elongated, and eight eyes arranged in two slightly curved rows.
Physical Description
Robust, elongated body with a broad cephalothorax and an oval abdomen. Covered in fine, velvety hairs. Females tend to have a larger, more robust abdomen compared to males, which possess noticeably longer legs and enlarged pedipalps.
Size Estimate
Body length ranges from 10 to 18 millimeters for females and 12 to 19 millimeters for males, with a substantial leg span reaching up to 45 to 75 millimeters.
Coloration & Markings
Mottled brown, dirty yellow, and grey coloration. The carapace features distinct longitudinal yellowish or pale markings, while the abdomen displays a characteristic lighter herringbone or chevron pattern running down the center.
Web Type
Constructs a flat, dense sheet web that ends in a tubular retreat where the spider hides, waiting for prey to walk across the sheet.
Eye Arrangement
Eight small eyes of roughly equal size arranged in two nearly straight horizontal rows across the front of the cephalothorax.
Leg Characteristics
Long, relatively thick, and covered in prominent spines and hairs. The legs lack extreme banding but often appear uniformly dark brown. They are held sprawled outward in a typical hunting posture.
Venom & Safety Information
Venom Information
Neurotoxic venom used to immobilize insect prey. It is low in potency relative to humans and is generally considered non-dangerous.
Medical Significance
Not medically significant. Bites are rare, typically occurring only when the spider is trapped directly against human skin. Symptoms are usually mild, limited to localized pain and slight redness, akin to a minor bee sting.
Safety Recommendations
Avoid handling them bare-handed to prevent accidental bites. If relocation is needed, cover the spider with a container, slide a piece of paper underneath, and release it outdoors.
Habitat & Behavior
Habitat & Range
Native to Europe and introduced to North America and parts of Central Asia. Found primarily in dark, sheltered areas such as cellars, garages, woodpiles, and dark corners of houses.
Behavior & Temperament
Timid and fast-moving. They are primarily nocturnal hunters that rely on the vibrations of their sheet web to detect prey. They generally flee from humans rather than show aggression.
Diet & Prey
Insects and other arthropods, including cockroaches, flies, beetles, and occasionally other spiders.
Seasonal Activity
Most commonly seen in late summer and autumn when mature males leave their webs to roam in search of females.
Description
The Giant House Spider is one of the largest common household spiders found within its range. Known for its impressive speed and sprawling leg span, it is often encountered scurrying across floors in late summer as mature males wander in search of mates. Despite its intimidating size, it is a shy and beneficial inhabitant of dark corners and cellars.
Key Features
Large size, velvety appearance, mottled brown coloration with a distinct abdominal herringbone pattern, and construction of a flat sheet web ending in a funnel retreat.
Similar Species
Tegenaria domestica (Barn Funnel Weaver), which is generally smaller and features more distinctly banded legs. Wolf Spiders (Lycosidae) are also similar in appearance but do not build webs.
Life Cycle
Females construct silken egg sacs in autumn, depositing dozens of eggs. Spiderlings hatch in spring, undergo multiple molts over a period of two to three years, and reach maturity by late summer or autumn.
Ecological Importance
Acts as an effective natural pest control agent by keeping populations of household insects and other arthropods in check.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and common throughout their range.
Interesting Facts
Giant house spiders are remarkably fast sprinters, capable of reaching speeds up to 0.5 meters per second, earning them a place in past Guinness World Records for spider speed.
Photography Tips
Use a macro lens with natural or diffused lighting to capture the fine details of the carapace and abdominal pattern. Keep a safe distance and photograph from a low angle to highlight the leg span.
Identified: 2026-09-28T15:05:19.902884