Is it a Hobo Spider?

Asked May 31, 2015, 11:06 PM EDT

I have seen tons of these in our house in Morro Bay, California (landlord frequently travels out of the state; Utah to be specific).

I am wondering if this could possibly be a hobo spider or if it is something else that is harmless?

Thanks!

San Luis Obispo County California insect issues urban integrated pest management spiders

1 Response

I doubt that any of your specimens are hobo spiders. Judging from the scientific literature, it appears the toxicity of hobo spider venom is not as was first reported. Even the CDC was fooled in a report they issued almost 20 years ago on venomous spiders.

Spiders get blamed for a lot of problems around the home without any clear evidence of their involvement. People are easily frightened of spiders, especially in the house---regardless of the size or species of the spider. Having worked with an arachnologist for quite a few years at NMSU, spiders submitted to him as potentially dangerous have never had any association with venomous attacks on anything but their usual arthropod prey and most were too small or their fangs were too small to bite into or through human skin anyway.

Probably the best source of scientific information on hobo spiders is Rick Vetter from the University of California, Riverside. He has a University of California Pest Notes 7488, 3 pages, that may be helpful. On the web, access: www.ipm.ucdavis.edu/PMG/PESTNOTES.

Over the years since hobo spiders have been in the news, he and colleagues questioned the horror stories in the popular press about spider bites in general and hobo spiders in particular. In one project he worked with the medical literature from the Pacific Northwest associated with spider bites, BUT ONLY with reports where the actual spiders involved were submitted for identification by knowledgeable arachnologists, Vetter and colleagues discovered that hobo spiders, even where the spiders are known to occur, were involved in very few confirmed biting incidents; further, even those few incidents did not result in the consequences reported in great detail in the popular press.

Whether in the emergency room or a doctor's office, people may attribute their problems to spider bites, but they offer no definitive proof that particular spiders actually caused their problems. In some cases, at least, skin infections develop from puncture wounds, but wounds not made by spiders. Since there likely are no definitive tests to detect the type or amount of venom involved in any of these presumed spider bite cases, the patient is more likely treated with something 'just to be sure' and avoid liability.

Another problem, too, with the hobo spider situation is that these spiders are blamed for bites in places where hobo spiders have never been collected.

Vetter and colleagues have another fact sheet (actually 7 pages long) about identification of hobo spiders vs other spiders. Colors and marking patterns are not diagnostic since many totally unrelated species appear similar. As with other arthropods, but especially with spiders, definitive features are not easily seen or interpreted from the ID keys by laymen. You can find that publication on-line also.

I hope this is helpful. From what I understand hobo spiders have been in the Pacific Northwest for as long as 90+ years; they seem to be staying in this area, also. Presumed hobo spiders from New Mexico and elsewhere just haven't been confirmed using real specimens.