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 eight eyes arranged in two slightly curved rows.
Physical Description
Robust body with a brown or grayish cephalothorax featuring distinct longitudinal pale markings and a mottled abdomen. The body is covered in fine setae (hairs), giving it a velvety appearance. Females are generally larger and heavier-bodied than males.
Size Estimate
Body length ranges from 10 to 18 mm for females and slightly smaller for males, with a total leg span that can reach up to 75 to 100 mm. This specimen appears to be an adult.
Coloration & Markings
Composed of earthy tones including dark brown, yellowish-brown, and gray. The cephalothorax has characteristic light-colored longitudinal stripes or patches, and the abdomen features a distinct mottled, chevron-like or herringbone pattern down the dorsal side.
Web Type
Constructs a flat, dense sheet web that funnels into a tubular retreat where the spider hides, typically located in dark, sheltered corners, basements, or woodpiles.
Eye Arrangement
Eight small, dark eyes of roughly equal size arranged in two nearly straight or slightly curved horizontal rows across the front of the cephalothorax.
Leg Characteristics
Long, robust legs covered in visible spines and faint dark banding. The legs are well-adapted for rapid running across surfaces rather than climbing smooth vertical walls efficiently.
Venom & Safety Information
Venom Information
Contains neurotoxic venom used to subdue invertebrate prey. It is generally not dangerous to humans and has very low medical significance.
Medical Significance
Harmless to humans. Bites are extremely rare because they prefer to run away; if a bite occurs, it typically results in mild, localized pain and temporary redness comparable to a bee sting.
Safety Recommendations
Keep living areas clean and seal entry points if you wish to limit encounters. If relocation is desired, gently guide the spider into a container using a piece of cardstock and release it outdoors.
Habitat & Behavior
Habitat & Range
Native to Europe and introduced to parts of North America (particularly the Pacific Northwest). Prefers cool, dark, undisturbed areas such as cellars, garages, woodpiles, and stone walls.
Behavior & Temperament
Timid and fast-moving. It flees rather than fights when disturbed, though mature males can become more active and defensive during autumn mating season while searching for females.
Diet & Prey
Generalist predator feeding primarily on crawling insects such as beetles, roaches, flies, and other spiders, capturing them when they blunder onto the sheet web.
Seasonal Activity
Most commonly seen in late summer and autumn, when mature males leave their webs to wander in search of mates, frequently leading to indoor encounters.
Description
The Giant House Spider is one of the largest spiders commonly encountered in human dwellings. Known for its impressive leg span and surprising speed, it spends most of its time hidden within its signature funnel web. Despite its intimidating appearance, it is a peaceful and beneficial resident that helps control household insect populations.
Key Features
Large size, long spiny legs, mottled brown abdomen with a herringbone pattern, light markings on the cephalothorax, and association with a flat sheet web ending in a funnel retreat.
Similar Species
Tegenaria domestica (Barn Funnel Weaver) and Eratigena agrestis (Hobo Spider). E. atrica is generally much larger and darker, and microscopic examination of genitalia or sternum patterns is often required for definitive separation.
Life Cycle
Females produce disc-shaped egg sacs in autumn, guarding them through the winter. Spiderlings hatch in spring, undergoing multiple molts to reach maturity within two to three years. Adults typically live for several years.
Ecological Importance
Acts as an effective natural pest controller by preying on common household and garden insects, helping to regulate populations of flies, beetles, and roaches.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and abundant across their native and introduced ranges.
Interesting Facts
Giant House Spiders were once holders of the Guinness World Record for top spider running speed, capable of reaching speeds up to 1.73 feet per second (0.5 meters per second).
Photography Tips
Use natural lighting or an external diffuser to capture the detailed herringbone pattern on the abdomen and the spination on the legs. Maintain a respectful distance to avoid startling the spider into fleeing.
Identified: 2026-08-25T18:51:23.302022