Are Hobo Spiders Venomous? The Truth About Their Bite

Hobo spiders produce venom, as nearly all spiders do, but the evidence accumulated over the past two decades has consistently failed to support the claim that their bite causes the tissue-destroying wounds once attributed to them. The spider’s reputation as a medically dangerous species traces back to a single animal study from the 1980s, and what researchers have found since paints a very different picture. In fact, the one verified hobo spider bite documented in a peer-reviewed study of Oregon spider bites caused minor pain and redness that cleared up within twelve hours.

Where the Dangerous Reputation Came From

The hobo spider (now classified as Eratigena agrestis, formerly Tegenaria agrestis) is a funnel-web spider originally from Europe that became established in the Pacific Northwest of North America by the mid-twentieth century. Its reputation as a dangerous species rests almost entirely on a toxicology study in which researchers induced hobo spiders to bite rabbits, and skin lesions developed at the bite sites.¹ Those rabbit results were extrapolated to humans, and by the 1990s the hobo spider had been widely labeled as one of three medically significant spiders in North America, alongside the brown recluse and the black widow.

The problem is that rabbit skin reacts to spider venom very differently than human skin does. Rabbits develop necrotic lesions from the venom of many spider species that are completely harmless to people. Researchers who have scrutinized the original rabbit work have pointed out that the leap from rabbit dermonecrosis to human danger was never supported by clinical evidence in actual human bite victims. What followed was decades of the hobo spider being blamed for skin wounds in the Pacific Northwest with little to no verification that a hobo spider was actually involved.

What a Verified Hobo Spider Bite Actually Does

One of the clearest pieces of evidence comes from a study that collected and verified spider bites across the state of Oregon. Researchers gathered 33 confirmed bites from multiple spider species, including bites from funnel-web spiders in the same family as the hobo spider. None of the bites produced significant medical symptoms, and none caused dermonecrosis, the tissue-destroying wound that hobo spiders had been blamed for.² The single verified hobo spider bite in the study produced pain, redness, and some twitching in the person’s calf muscle. Everything resolved within about twelve hours.

That pattern, minor local irritation that fades quickly, is consistent with what you would expect from the bite of a small, non-dangerous spider. It looks nothing like the alarming photographs of deep, crater-like wounds that circulated on the internet for years under the label “hobo spider bite.” The researchers had set out specifically to assess whether hobo spiders possess toxic venom. Their conclusion was that the evidence for toxicity simply was not there.

Testing the Venom Directly

Beyond tracking bite outcomes, researchers have examined hobo spider venom in the laboratory to see whether it can damage vertebrate tissue. One study tested the venom’s ability to destroy red blood cells, a standard measure of how harmful a spider’s venom is to vertebrates. The result was clear: hobo spider venom was not harmful to vertebrate red blood cells, confirming what earlier studies had also found.³ If the venom can’t even break down blood cells in a lab dish, it’s difficult to argue that it could destroy skin and deeper tissue in a living person.

This matters because the specific accusation against hobo spiders was that their venom causes necrosis, the death of living tissue that produces those dramatic open wounds. A venom capable of doing that would typically show strong activity against cells in lab assays. The hobo spider’s venom does not. It appears to be a venom well-suited for subduing the small insects that make up the spider’s diet, but largely inert when it comes to human tissue.

Hobo Spiders Have Not Been Reliably Linked to Necrotic Wounds

A comprehensive review published in Canadian Family Physician examined the broader pattern of spider bite attribution in Canada and reached a stark conclusion: hobo spiders have not been reliably implicated in dermonecrosis.⁴ The review found that worldwide, spider bites are regularly misdiagnosed as the cause of necrotic skin wounds, driven by inaccurate popular and professional literature built on circumstantial evidence and flawed clinical trials.

That phrasing, “erroneous attribution,” is worth sitting with. The medical literature isn’t saying hobo spider bites are merely less dangerous than once thought. It’s saying that the entire framework of blaming hobo spiders for necrotic wounds was based on poor evidence from the start: inference rather than documentation, assumption rather than verification. In most reported cases where a hobo spider was supposedly responsible, no spider was actually captured and identified. The diagnosis was based on the patient’s location (Pacific Northwest), the appearance of the wound, and the assumption that hobo spiders must be the cause.

What “Spider Bite” Wounds Usually Turn Out to Be

If hobo spiders aren’t causing those alarming skin lesions, what is? In many cases, the answer is bacterial infection. A study of patients who came to emergency departments believing they had been bitten by a spider found that only about four percent actually had spider bites. Roughly 86 percent turned out to have skin and soft-tissue infections instead.⁵ The remaining patients had bites from other animals or other conditions entirely.

One particularly well-documented example involves MRSA, a drug-resistant staph infection that can cause red, swollen, painful skin lesions. At several military facilities, outbreaks of mysterious skin wounds were initially blamed on spider bites. When researchers actually cultured the lesions, they found MRSA, not venom.⁶ This isn’t an isolated incident. There remains a widespread bias among both the public and healthcare workers to attribute skin infections to spiders, even when there’s no evidence a spider was involved.⁷

The practical consequence of this misdiagnosis pattern is serious. A bacterial infection like MRSA requires antibiotics and sometimes surgical drainage. If you assume your wound is a spider bite and wait for it to heal on its own, a treatable infection can spread and become dangerous. The instinct to blame a spider can delay the treatment you actually need.

Why the Myth Persists

You would think that years of accumulating evidence would have put the hobo spider’s dangerous reputation to rest. The CDC quietly removed it from their list of venomous spiders of medical concern years ago. Yet the myth lingers, and there are a few reasons why.

First, once a spider earns a scary reputation, media coverage tends to reinforce it. Research on how spider-related news stories influence public behavior has found that sensationalistic coverage of spiders drives a measurable spike in online searching about spider dangers.⁸ People see a frightening story, search for more information, and find older sources that still repeat the outdated claims. The cycle reinforces itself.

Second, confirmation bias plays a powerful role in spider bite attribution. If you wake up with a painful red lump and you’ve seen hobo spiders in your house, it feels logical to connect the two. The spider becomes the explanation because it’s visible and scary, while the actual cause, often a bacterial infection picked up through a minor scratch or skin abrasion, is invisible. Humans are storytelling creatures, and “a spider bit me in my sleep” is a much more compelling narrative than “bacteria entered through a micro-abrasion I didn’t notice.”

Third, some professional medical literature from the 1990s and early 2000s included hobo spiders as a cause of necrotic arachnidism, and those references continue to circulate in older textbooks and clinical resources. Doctors who trained during that era may still carry the assumption, and patients who search medical databases may encounter those outdated papers before finding the more recent refutations.

The Giant House Spider Problem

Identification adds another layer of confusion. The hobo spider is frequently confused with the giant house spider (Eratigena atrica), a close relative in the same genus that also builds funnel-shaped webs and is common in homes across the Pacific Northwest. The Oregon bite study specifically noted that among their verified funnel-web spider bites, one came from a hobo spider and another from a giant house spider, which is “readily confused” with its smaller cousin.² Neither bite caused anything more than minor symptoms.

Telling the two apart without a microscope is genuinely difficult, even for people who know what to look for. Both are brown, leggy, and about the same general shape. The giant house spider tends to be larger, with leg spans that can reach over three inches, while hobo spiders are typically a bit smaller. But size varies with age and sex, making it an unreliable field marker. The chevron-like markings on the abdomen that some guides describe for hobo spiders also appear, in slightly different patterns, on giant house spiders. Without examining the spider’s reproductive structures under magnification, positive identification is unreliable.

This identification difficulty matters because many “hobo spider bite” reports likely involved giant house spiders or other harmless funnel-web species. When someone can’t reliably identify the spider that supposedly bit them, the entire attribution chain collapses. And in many reported cases, no spider was seen at all. The patient simply assumed a spider was responsible because the wound looked like what they imagined a spider bite should look like.

What Actually Happens When a Spider Bites You

To put hobo spider bites in context, it helps to understand what most spider bites feel like. The vast majority of spiders in North America that can pierce human skin produce a bite comparable to a bee sting or less: localized pain, some redness, maybe mild swelling that resolves in a few hours to a day. Hobo spider bites, based on the limited verified cases available, fit squarely in this category.

The two spiders in North America whose bites genuinely warrant medical concern are the black widow and the brown recluse. Black widow bites can cause systemic symptoms including muscle cramps, nausea, and elevated blood pressure due to a neurotoxic venom. Brown recluse bites can, in a minority of cases, cause a spreading necrotic wound, though even these are less common and less severe than popular accounts suggest. The hobo spider has nothing in common with either of these spiders in terms of medical risk. Its venom simply does not produce effects beyond the local irritation you would get from any minor spider bite.

If you’re bitten by any spider and the bite area starts showing signs of spreading redness, increasing warmth, fever, or pus, seek medical attention. But suspect an infection, not venom. Those are signs that bacteria may have entered the wound, and that’s a problem antibiotics can address. Waiting because you think “spider venom needs to run its course” is the wrong move.

Living with Hobo Spiders

Hobo spiders are common in the Pacific Northwest, particularly in basements, garages, window wells, and ground-level areas of homes. They build flat, funnel-shaped webs in sheltered spots and are most often encountered in late summer and early fall, when males leave their webs to search for mates and end up wandering into living spaces.

Because their bites are not medically significant, hobo spiders don’t warrant the kind of aggressive control measures that people sometimes pursue. You can reduce encounters by keeping clutter to a minimum in storage areas, sealing gaps around windows and doors, and using sticky traps in areas where you’ve seen spiders. If you find one in your house, it can be captured in a glass and released outside. Spraying pesticides in an attempt to eradicate hobo spiders is largely unnecessary and can create more problems than it solves, particularly if you have pets or children.

If anything, hobo spiders are useful housemates. They feed on insects and other small arthropods, acting as free pest control. The spider sitting in the corner of your garage is far more interested in catching flies than in biting you. Bites typically happen only when a spider is accidentally trapped against skin, such as when you put on a shoe or gardening glove the spider has crawled into. Shaking out clothing and shoes that have been sitting in storage is a simple habit that prevents the vast majority of incidental spider bites of all kinds.

When Spiders on Your Skin Carry Bacteria Along for the Ride

One finding that doesn’t get much popular attention is that spiders can mechanically transfer bacteria when they bite. The same study that tested hobo spider venom’s effect on blood cells also looked at the bacteria spiders carry on their fangs and body surfaces.³ Spiders walk through dirt, debris, and the remains of their prey. Their fangs are not sterile. When a spider punctures your skin, it can introduce bacteria into the wound, just as a splinter or thorn would.

This creates an ironic situation. In the rare cases where a spider bite does lead to an infection that produces a nasty-looking wound, the culprit isn’t the spider’s venom at all. It’s the bacteria that hitched a ride on the spider’s mouthparts. The wound looks bad not because the venom is toxic to humans, but because a bacterial infection took hold in the puncture site. Clean any spider bite with soap and water and keep an eye on it, just as you would any minor skin puncture. The goal is to prevent secondary infection, not to neutralize venom.