The hobo spider has finally claimed its reputation that was taken for many years by the brown recluse spider as the most dangerous arachnid of the Pacific Northwest. Since its introduction to American through the port of Seattle on goods shipped from Europe, this spider has been responsible for countless human bites. The end of the 20th century showed its habitat extending into Colorado, Utah, Idaho, and California.
Tegenaria agrestis originated in Western Europe as the "mat weaver of the field." This is because the hobo spider doesn't weave sticky webs to catch flying insects, but spins funnel-shaped mats near the ground. When insects walk on top of or into the funnel, the hobo spider darts out from its "trick web" hiding place and attacks the prey with a poisonous bite. This method of catching food makes the hobo a very aggressive spider in the wild. But when it adapted to city living in America, and began living in close proximity to houses, it became a danger to people as well.
The hobo spider can be identified as a large, brown spider with swollen sacs at the front (male) and a herringbone V-pattern underneath its abdomen. They are predominantly ground, not climbing, spiders that travel around houses and businesses. Chemical fumigation often just kills the hobo spider's competitors. Sticky traps, while effective indoors, puts people in direct contact with a possibly live specimen. Its difficult to significantly reduce their population through fumigation.
The venom of the hobo spider is so dangerous, it's one of a few arachnids listed on the Center for Disease Control's list of poisons. Even though only 50% of bites inject venom and result in tegenarism, the hobo is responsible for more human bites in Northeast America than any other spider. These bites are rarely fatal. At first, the bite spot might resemble a mosquito bite without the itching. After a day, the bite forms a blister that bursts to reveal an open sore. At this stage, unless the victim seeks medical attention, the sore can widen and deepen and cause much tissue damage. The wound will be very slow to heal, leaving noticeable scars.