The Giant House Spider (GHS) is a striking arachnid whose size often inspires more fear than its actual biology warrants. Despite its large appearance, the GHS is not considered dangerous to humans and has extremely low medical significance. Apprehension stems primarily from its speed and impressive leg span, which can be startling when encountered unexpectedly inside a home. Its instinct is to flee from humans, and its venom is not potent enough to cause serious harm to mammals. While the spider is venomous, any bite is generally comparable to a mild sting.
Clarifying the Risk: Venom, Not Poison
The terms “venomous” and “poisonous” are often used interchangeably, but they describe two different biological mechanisms. A substance is considered venom if it is actively injected into another creature using a specialized delivery system, such as fangs or stingers. In contrast, a substance is classified as poison if it is toxic when ingested, inhaled, or absorbed through the skin. All spiders, including the Giant House Spider, are venomous because they use fangs to inject a cocktail of toxins into their prey.
The venom produced by the Giant House Spider is designed to immobilize and digest the small invertebrate prey it typically consumes, such as insects. The chemical components of the venom are effective against insect physiology but are not well-suited to causing significant damage to a large mammal like a human. Spiders use their venom as a tool for hunting, and wasting it on a creature too large to eat is counterproductive.
Recognizing the Giant House Spider
Identifying the Giant House Spider, whose scientific name is Eratigena atrica (or a closely related species), often comes down to its sheer size and coloration. These spiders have earthy tones, typically appearing dark brown with subtle markings of gray or black on the body. The legs and body are noticeably hairy, giving them a robust appearance.
While the body length of a mature female is relatively modest, their leg span is what earns them their name. Males, which are slightly smaller in body size, can have a highly variable leg span, sometimes reaching up to 4 inches (10 cm). They construct flat, messy webs with a funnel-shaped retreat, usually found in undisturbed, dark corners. Giant House Spiders typically prefer secluded outdoor spaces like woodpiles, rock gaps, and sheds, but they frequently enter homes, particularly in the autumn, often in search of mates or shelter.
Rarity and Reality of a Bite
The Giant House Spider is a shy arachnid that prefers to retreat when disturbed, famously recognized as one of the fastest spiders in the world, running up to half a meter per second to escape danger. A bite is an extremely rare event that only happens when the spider feels trapped, such as if it is accidentally squeezed against the skin or aggressively handled.
If a bite does occur, the sensation is typically described as a minor sting or a pinprick, and the outcome is generally non-threatening. Symptoms are usually limited to the bite site and may include localized redness, minor swelling, and temporary mild pain. Basic first aid involves cleaning the area with soap and water to prevent secondary infection and applying a cold compress to reduce swelling. The minor symptoms typically resolve completely within a day or two.