Giant House Spider
Eratigena atrica
Agelenidae (Funnel-Weavers), Order Araneae. Key family characteristics include three pairs of spinnerets with the posterior spinnerets notably elongated, and building characteristic sheet webs leading to a tubular retreat.
Physical Description
The spider has a robust body with an elongated oval abdomen and a distinct, slightly darker cephalothorax. The texture appears moderately hairy. The proportions feature long legs radiating outwards, typical of funnel-weavers. This individual appears to be an adult or sub-adult male due to the slender abdomen and slightly enlarged palps visible near the head.
Size Estimate
Body length is approximately 10 to 18 millimeters, with a total leg span reaching up to 45 to 75 millimeters. This falls well within the typical range for an adult giant house spider.
Coloration & Markings
Base coloration consists of various shades of brown, ranging from yellowish-brown to dark brown. The cephalothorax typically has lighter yellowish longitudinal stripes, while the abdomen features a mottled pattern with a paler central band flanked by dark spots or chevrons.
Web Type
Builds a dense, non-sticky sheet web (funnel web) that extends across a flat surface, often in corners, leading into a tubular retreat where the spider waits for prey.
Eye Arrangement
Eight small eyes arranged in two slightly curved, horizontal rows of four across the anterior portion of the cephalothorax, typical of the Agelenidae family.
Leg Characteristics
Long, robust legs covered in fine hairs and visible spines. The legs are typically light brown with faint darker banding. They are held flat against the surface in a sprawling posture when resting.
Venom & Safety Information
Venom Information
Possesses mild neurotoxic venom used primarily to subdue insect prey. It is not considered dangerous or medically significant to humans.
Medical Significance
Harmless to humans. Bites are extremely rare, typically only occurring if the spider is directly squeezed or trapped against human skin. Symptoms from a bite are generally minor, akin to a mild bee sting with slight local redness and swelling.
Safety Recommendations
No special safety measures are required as they are harmless. If relocation is desired, gently place a cup over the spider, slide a piece of paper underneath, and release it outdoors.
Habitat & Behavior
Habitat & Range
Found widely across Europe and introduced to parts of North America, particularly the Pacific Northwest. Prefers dark, undisturbed areas such as cellars, attics, sheds, and behind furniture in homes, as well as woodpiles and hollow trees outdoors.
Behavior & Temperament
Generally docile and highly skittish, preferring to flee rapidly to its funnel retreat when disturbed. They are primarily nocturnal hunters, running down prey on their sheet webs.
Diet & Prey
Feeds primarily on various household insects, including flies, mosquitoes, roaches, and beetles, using speed and ambush tactics on its web.
Seasonal Activity
Most commonly seen in late summer and autumn, when mature males leave their webs to actively search for females during the mating season.
Description
The giant house spider is one of the largest common household spiders, frequently startling homeowners with its impressive leg span and rapid, darting movements. Despite its formidable appearance, it is a beneficial and harmless resident that helps control insect populations indoors.
Key Features
Long, hairy legs, mottled brown and yellowish patterning on the abdomen, elongated posterior spinnerets, and association with dense funnel-shaped sheet webs in dark corners.
Similar Species
Can be confused with other funnel-weavers like Eratigena agrestis (hobo spider) or Tegenaria domestica (barn funnel weaver). Distinguishing usually requires close examination of genital structures under magnification.
Life Cycle
Females construct disc-shaped egg sacs in late autumn, containing dozens of eggs, and guard them until they hatch. Spiderlings disperse in spring, molting multiple times over two to three years to reach maturity.
Ecological Importance
Acts as an effective natural pest control agent in domestic and outbuilding environments, regulating populations of nuisance insects.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and often thriving in human-modified environments.
Interesting Facts
Despite their intimidating size and speed—capable of running up to 0.5 meters per second—they have very poor eyesight and rely almost entirely on vibrations felt through their web.
Photography Tips
Use a macro lens with adequate lighting to capture dorsal markings and eye arrangement. Maintain a steady hand as they may bolt suddenly if disturbed by sudden movements.
Identified: 2026-08-24T13:30:41.187007