Do hobo spider bites cause dermonecrotic injuries?

In 1987, the hobo spider, Tegenaria agrestis, was initially implicated in necrotic lesions in the Pacific Northwest of the United States. This European-origin species has since joined the widow and recluse spiders to become the well-known trio of medically significant spiders in North America. It is currently distributed from British Columbia to Oregon and east to Montana and Colorado, with eastward expansion still occurring. Yet, because of the spider’s notoriety, people throughout the United States assume that hobo spiders are locally present, and physicians have diagnosed bites in California where hobo spiders have never been documented. Worldwide, spiders have routinely been implicated in necrotic lesions. In some cases, however, these incriminations were based on poor clinical reporting, insufficient research, circumstantial evidence, or extrapolations from necrotic effects of venom in animal models. For example, in South America, wolf spiders were blamed for causing necrotic ulcers in the 1920s on the basis of suspected cases. This prompted studies in animals demonstrating that large quantities of venom injected intradermally caused necrosis, but necrosis was not caused when venom was injected subcutaneously or intramuscularly. Antivenom was developed and used in Brazil, and wolf spiders in other parts of the world were blamed for necrotic ulcers by association. However, subsequent documentation of 515 verified bites manifested no necrotic ulcers. Unfortunately, wolf spiders are still blamed for necrotic