The above is incorrect with regards to Hobo spiders and their ability to cause massive infections.
Hobo spiders which are now very common in the Northwest US are known to cause severe lesions and secondary infections.
Hobo spiders are known as Tegenaria agrestis, with two other members in the same genus also being very common in the same ranges, especially in the Northwest; they being the smaller and inpotent Tegenaria domestica (mat weaver of the house) and Tegenaria gigantea (Gigantic mat weaver). The latter of these two can grow to disturbing sizes, and is nearly identical to the hobo spider, often being confused with it.
Now, necrotic wounds are commonly attributed to brown recluses in the NW by doctors and people alike. This would be fine and well, except recluse spiders have never been found in the NW. Prior to Tegenaria’s probable introduction in Seattle from Europe there was very little recluse blaming activity. Starting in the 1940’s doctors began seeing patients with severe necrosis, and could only pin the problem on recluses which the bites resembled.
Since T. agrestis was not known to be common in the northwest, it was understandable that these necrotic lesions be attributed to a spider that was known to cause such problems. But a professor at WSU started a study to test the recluse theory. “In the late 1970s and early 1980s this mystery came to the attention of toxinologist Darwin Vest, an autodidact whose work on cobras, rattlesnakes, and other venomous creatures had won him respect. While working at Washington State University in Pullman, Vest learned that the local zoology department often received queries about necrotic arachnidism—flesh-killing lesions apparently caused by spider bites. Vest looked into the cases of 75 patients in the Pacific Northwest. He blamed most of the injuries on insect bites, cigarette burns, and other causes. But that left 22 cases. Vest and his team surveyed the homes of these patients, collecting thousands of specimens by hand and with sticky traps. None of the homes yielded brown recluses, but 16 of them revealed healthy populations of hobo spiders. Sometimes a single sticky trap would fill with hoboes in a week’s time.” (Discover magazine, vol 26 no 9) and after milking the spiders and injecting into rabits, it was found to cause necrotic lesions. However the results were not found to be reproducable. However, it has been found that necrotic cases do coincide in frequency with mating times for hobo spiders (early to mid summer).
As for T. gigantea, although not known to be responsible for venemous necrotic reactions, they are of remarkable size (leg span of a hand palm or more, the author having seen one of that size on a stairwell at the University of Washington). They have fangs more than big enough to cause massive secondary infections to regions they bite. These infections are no easy business, as they can cause necrosis themselves, or worse yet, systemic infections. In the northwest, where spiders tend to be quite small and seldom venture inside the house (with exception to black widows), T. Gigantea is by far the largest common housespider of the northwest, and the most likely culprit to any secondary infection caused by bugbite.
In general however, Tegenaria species are very timid species. Usually they confine themselves to the area around their web, unless disturbed. They do not bite unless harrased, and even then the bites are usually dry. They do venture out in mating season, during summer. So unless the bite occured in summer, or you saw the Tegenaria species actually bite you, it probably isn’t a hobo or gigantea bite.
In closing, if the hobo spider is not dangerous, then why does the CDC seem to think otherwise? http://aepo-xdv-www.epo.cdc.gov/wonder/prevguid/m0042059/m0042059.asp
