The hobo spider (Eratigena agrestis) is common in the Pacific Northwest of the United States, where it was introduced from Europe. This medium-sized, brownish funnel-web weaver often sparks concern. This fear stems from a long-standing belief that its bite causes severe tissue damage. Understanding the risk requires examining its history and the modern scientific understanding of its venom.
The History of the Hobo Spider Venom Myth
For decades, the hobo spider was wrongly classified as a “medically significant” arachnid, capable of inflicting bites that resulted in necrotic lesions (the death of skin tissue). This myth took hold after the spider became established in the Pacific Northwest, a region outside the natural range of the brown recluse spider (Loxosceles reclusa). People presenting with unidentifiable necrotic skin wounds were often assumed to have been bitten by the hobo spider, as it was a common large spider found in homes.
Early, small-scale studies, including one in 1987 involving rabbits, appeared to support the link between hobo spider venom and dermonecrotic effects. However, subsequent, more rigorous clinical and toxicological reports have consistently failed to replicate these results in animal models. The scientific consensus is that the hobo spider is not of medical concern and its venom is not potent enough to cause tissue death in humans. The Centers for Disease Control and Prevention (CDC) removed the hobo spider from its list of venomous species in 2017, acknowledging the lack of evidence for dangerous venom.
Identifying the Hobo Spider in Your Home
Identifying the hobo spider can be challenging, as it shares a similar appearance with several other common, harmless house spiders in the funnel-web family. It is typically light to medium brown, with a body length ranging from 7 to 14 millimeters and a leg span up to two inches. A distinguishing feature is a pattern of chevron or herringbone markings on the abdomen, with the points of the “V” shapes facing the head.
Unlike many other spiders, the hobo spider lacks distinct dark bands on its legs and has indistinct or diffused markings on the cephalothorax (the front body section). Hobo spiders are often confused with the Giant House Spider (Eratigena atrica), a larger, non-threatening relative, or with the Brown Recluse. The Brown Recluse, which is not native to the Pacific Northwest, has a clear, dark, violin-shaped marking on its cephalothorax, which the hobo spider lacks.
Hobo spiders build a distinctive sheet-like web that funnels down into a tubular retreat, often constructed near the ground in woodpiles, window wells, or foundations. The web is non-sticky, and the spider waits at the narrow end of the funnel to ambush prey. The hobo spider is a fast runner but not a good climber, which is why it is usually found at ground level or in basements.
Symptoms and Treatment for a Confirmed Bite
A bite from a hobo spider is rare; the spider typically prefers to flee rather than bite, only striking if it feels trapped or provoked (such as when pressed against the skin). When a bite occurs, it is often described as painless or a slight prickling sensation. The consequences of a verified hobo spider bite are minimal and short-lived.
Typical symptoms are non-specific and resemble the reaction to minor insect bites: localized redness, mild swelling, and slight itchiness. In documented cases of confirmed hobo spider bites, the reaction did not progress beyond minor pain and redness that resolved within 12 hours. The primary danger from a suspected spider bite is often a misdiagnosis of a bacterial skin infection, such as Methicillin-resistant Staphylococcus aureus (MRSA), which causes necrotic-like lesions and is often mistaken for a spider bite.
If a person suspects a spider has bitten them, the recommended first aid is to clean the area thoroughly with soap and water. Applying a cold compress or ice pack helps reduce localized pain and swelling. Over-the-counter pain relievers or antihistamines can manage discomfort and itching. Medical attention should be sought if the bite area shows signs of secondary infection (spreading redness, pus, or a fever), as these symptoms indicate a problem more serious than the hobo spider’s mild venom.