Giant House Spider
Eratigena atrica
Agelenidae (Funnel-web weavers), Order Araneae. Key family characteristics include three pairs of spinnerets with the posterior pair being noticeably elongated, and constructing sheet webs that lead into a tubular retreat.
Physical Description
The giant house spider has a robust, oblong abdomen and a distinct, broad cephalothorax. The body is covered in fine setae (hairs), giving it a velvety appearance rather than a shiny one. Females are typically larger and bulkier than males, while mature males possess noticeably longer legs and enlarged pedipalps at the front of the head.
Size Estimate
Body length ranges from 10 to 18 mm for females and 12 to 19 mm for males, with an impressive total leg span that can reach up to 75 to 100 mm (3 to 4 inches). The specimen shown is a large adult.
Coloration & Markings
Coloration ranges from earthy brown to dark yellowish-brown. The cephalothorax features pale, yellowish markings, while the abdomen typically displays a mottled or chevron-like pattern down the center, flanked by lighter spots.
Web Type
Constructs a dense, non-sticky sheet web (funnel web) that is typically built in dark, undisturbed corners, behind furniture, or in basements and sheds. The web features a tubular retreat at one end where the spider waits for prey.
Eye Arrangement
Eight small, dark eyes arranged in two slightly curved, horizontal rows of four across the front of the clypeus, typical of funnel-web weavers.
Leg Characteristics
Long, robust legs covered in fine hairs and prominent spines. The legs are held in a sprawling, laterally extended posture typical of active ground-dwelling and web-associated hunters.
Venom & Safety Information
Venom Information
Possesses mild, neurotoxic venom designed to quickly immobilize insect prey. It is not considered dangerous to humans or pets.
Medical Significance
Harmless to humans. While capable of piercing human skin, their bites are extremely rare, non-toxic, and result in only mild, temporary localized discomfort similar to a mosquito bite.
Safety Recommendations
No emergency safety measures required. If found indoors, they can be safely relocated outside using a container and a piece of card. Sealing gaps under doors and reducing damp conditions will naturally deter them.
Habitat & Behavior
Habitat & Range
Native to Europe, Central Asia, and Northwest Africa, but successfully introduced to the Pacific Northwest of North America. Prefers damp, dark structural environments such as cellars, garages, woodpiles, and hollow spaces beneath floorboards.
Behavior & Temperament
Fast-moving, nocturnal hunters. They are generally timid and prefer to flee from disturbances rather than bite, though defensive strikes can occur if they are trapped or cornered.
Diet & Prey
Feeds primarily on various household and garden insects including flies, beetles, woodlice, moths, and other spiders. Prey is detected through vibrations on the sheet web.
Seasonal Activity
Most commonly seen in late summer and autumn (specifically September and October), when mature males wander extensively in search of females during the mating season.
Description
The giant house spider is one of Europe's and the Pacific Northwest's most prominent arachnid residents. Often startling homeowners due to its sheer size and blistering running speed, this impressive creature is actually a harmless and beneficial predator that helps keep insect populations under control.
Key Features
Distinguished by its large size, long spiny legs, mottled brown patterning, and preference for building funnel-shaped sheet webs in dark corners.
Similar Species
Can be confused with the Hobo Spider (Eratigena agrestis) or Wolf Spiders (Lycosidae). Unlike wolf spiders, giant house spiders build funnel webs rather than actively hunting in the open, and they tend to have a less contrasting, more velvety appearance than hobo spiders.
Life Cycle
Females produce disc-shaped egg sacs in autumn, guarding them through the winter. Spiderlings hatch in spring, undergo multiple molts, and reach maturity in one to two years, with a total lifespan typically ranging from two to three years.
Ecological Importance
Acts as a primary apex predator of smaller arthropods in human-altered and natural environments, effectively regulating indoor and outdoor insect pest populations.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and thriving globally, particularly in human-dominated landscapes.
Interesting Facts
Despite their intimidating appearance and speed (capable of running up to 0.5 meters per second), giant house spiders are poor climbers on smooth vertical surfaces and frequently fall into bathtubs or sinks.
Photography Tips
Use a macro lens with a fast shutter speed to freeze movement, as these spiders can dart away quickly. Side lighting helps highlight the tactile texture of the body and the intricate patterns on the abdomen.
Identified: 2026-08-09T19:57:52.223074