Hobo Spider

The hobo spider was first identified in Seattle, Wash., in 1930 after being introduced from Europe. Since the time of its introduction, this spider has spread throughout the northwestern United States and Canada. Its range includes the southern half of British Columbia, south to Oregon, and east to western Montana and the northwestern third of Utah.

The hobo spider is easily transported, and its range continues to expand. In May 1996, this species became the third spider to be placed on the “venomous spider” list by the Atlanta, Ga.-based Centers for Disease Control and Prevention.

Adult hobo spiders are large, brown and somewhat hairy, with a body length that can reach up to 0.6 of an inch with a leg span of one-and-a-half inches. The most distinctive feature of this spider is the multiple chevron (inverted “V”) patterns on the abdomen. These spiders have no stripes on their legs, which differentiates them from other domestic and giant spiders.

Hobo spider males can be differentiated from the females by the paired pedipalps (appendages) that resemble boxing gloves between its front legs. These expanded pedipalps are actually the male’s genitalia, not fangs. The females generally have a larger abdomen than males, and lack the enlarged pedipalps.

Hobo spiders make a characteristic funnel shape web with a tubular retreat or tunnel. Although they prefer to live outside in meadows or woodpiles, webs and egg cases will occasionally be found in basements or crawlspaces. Hobo spiders have a two-year life cycle.

Damage and Threat

Humans are most likely to encounter hobo spiders in late summer and fall. During this period, the males are very active in search of females, and will enter a home through ground level or below ground level openings.

Keep in mind that hobo spiders are medically important, because their bite can cause serious tissue damage and systemic illness. Males have a more venomous bite than females, and it is thought that immatures may have the most serious bite.

The effects of a hobo spider’s bite are similar to that of a brown recluse spider. The initial bite has been described as feeling like a pinprick, if it is felt at all. After about 30 minutes, however, a small hard area that resembles a mosquito bite appears. This is followed by an expanding red welt that may reach up to six inches in diameter. The bite begins to blister within 15 to 35 hours.

Hobo spider bites may also be accompanied by nausea, fever, headaches and joint soreness. Eventually, the wound scabs over, but may take months to heal. It usually leaves a permanent scar. Regardless, it is important to have the spider properly identified and immediately consult a physician.