The claim began with case reports from the 1980s associating slowly healing skin lesions in Washington and Oregon with Eratigena agrestis, an introduced European species that had become common around buildings.
The evidence did not hold. Reviews assembling verified bites, in which the spider was collected and identified, found no consistent necrosis. Attempts to reproduce the effect in laboratory animals failed, and the original supporting work could not be replicated. The strongest counter-argument came from Europe: the spider is native and abundant across a large part of the continent, where no comparable syndrome has ever been described. United States public health guidance was later revised to remove the hobo spider from lists of medically important spiders.
What did cause the original cluster remains open. Necrotic lesions have many sources, and bacterial infection, including drug-resistant staphylococcus, accounts for a substantial share of wounds blamed on spiders.