In fact, according to experts at Montana State University, there is only one spider in Montana considered medically significant to humans: the Western Black Widow. That's why the black widow earns its reputation as Montana's most dangerous spider. Brown Recluse - Photo by Timothy Dykes on Unsplash Brown Recluse - Photo by Timothy Dykes on UnsplashWhat about hobo and brown recluse spiders? Their nickname, "the aggressive house spider," is a misnomer based upon a translation error of its scientific name. Get our free mobile appMeanwhile, spider researchers have NEVER confirmed the presence of a brown recluse in the Treasure State.