Giant House Spider
Eratigena duellica
Agelenidae (Funnel-Weavers), Order Araneae
Physical Description
A large, spindly spider with a pear-shaped cephalothorax and an oval abdomen. Its body is covered in fine, short hairs giving it a velvety appearance. It possesses long, slender legs and prominent spinnerets at the rear.
Size Estimate
Body length: 10-18mm. Leg span: up to 75-100mm (3-4 inches). This specimen appears to be an adult, likely a male given the long leg-to-body ratio.
Coloration & Markings
Mottled brown, tan, and grey. The cephalothorax features two dark longitudinal stripes. The abdomen has a central pale mark with several pairs of 'chevron' spots extending towards the rear. Legs are typically a solid light brown without distinct banding.
Web Type
Funnel web. It builds a flat sheet of non-sticky silk with a funnel-shaped retreat at one end. Often placed in corners of basements, garages, or behind furniture.
Eye Arrangement
Eight small eyes of similar size arranged in two nearly straight rows. This arrangement provides excellent movement detection for hunting.
Leg Characteristics
Exceptionally long and thin. They are hairy but lack thick spines. In males, the legs are significantly longer than in females. They often rest in a flat, spread-out posture.
Venom & Safety Information
Venom Information
Contains neurotoxic proteins effective against insects but having low potency in humans. The venom is not considered medically significant.
Medical Significance
Harmless to humans. Bites are rare and typically involve only localized redness and minor swelling similar to a bee sting. No special treatment is required other than cleaning the site.
Safety Recommendations
If found indoors, they can be safely relocated using the cup-and-paper method. Wear gloves if you are hesitant. Ensure window screens are intact to prevent entry.
Habitat & Behavior
Habitat & Range
Common across Europe and the Pacific Northwestern United States and Canada. Primarily found in and around human dwellings, favoring dark, undisturbed areas like basements and crawl spaces.
Behavior & Temperament
Incredibly fast runners but generally timid. They are active nocturnal hunters that prefer to flee when disturbed. They are not aggressive and rarely bite unless pinned against skin.
Diet & Prey
Generalist predators of household insects including flies, silverfish, beetles, and even other spiders. They rely on speed to overtake prey on their silk sheets.
Seasonal Activity
Active year-round indoors, but most frequently encountered in late summer and autumn (August-October) when males wander into living spaces seeking females.
Description
The Giant House Spider is a common sight in temperate homes, often causing alarm due to its impressive size and legendary speed. Despite its name, it is a shy and beneficial roommate.
Key Features
Large leg span, mottled brown pattern, funnel-weaver eye arrangement, lack of leg banding, and two dark stripes on the cephalothorax.
Similar Species
Hobo Spider (Eratigena agrestis), which is smaller with shorter legs; Domestic House Spider (Tegenaria domestica), which is smaller and has banded legs.
Life Cycle
Females lay egg sacs containing up to 60 eggs, often incorporated into the web. Adults can live for several years. Males are most visible in late summer/autumn while searching for mates.
Ecological Importance
Natural pest controllers that significantly reduce the population of flies and other indoor insects. They serve as a food source for larger predators like birds and lizards.
Conservation Status
Not evaluated (Least Concern). Populations are stable and widespread due to their adaptation to human environments.
Interesting Facts
They are among the fastest spiders in the world, capable of running up to 0.5 meters per second. They are also known to outcompete and even prey upon the medically significant Hobo Spider.
Photography Tips
Use a macro lens to capture the chevron pattern on the abdomen. Side-on shots help show the leg span relative to the body. Natural light or soft flash is best to avoid glints on silk.
Identified: 2026-06-18T17:34:57.101098