The Hobo Spider

THE HOBO SPIDER Most spiders are beneficial, preying on insects, mites, and other spiders. However, there is one species, the hobo spider, that resides in this area and whose bites can be hazardous to humans. Many people mistakenly confuse the hobo spider with the brown recluse spider. We do not have brown recluse spiders in the Pacific Northwest. The hobo spider and two of its similar-looking relatives, the domestic house spider and the giant house spider, are commonly found in houses and yards here. The domestic spider is the most commonly encountered spider in the house and is the smallest spider of the three (less than one- half inch in body length). Generally, the hobo spider is medium to medium large, and the giant house spider is very large. The domestic and giant house spiders are not dangerous to humans. The body of the hobo alone can be up to three-quarters inch in length in mature adults. What will stand out the most is the multiple chevron pattern on the abdomen. Legs of the hobo spider have no stripes (different from domestic and giant spiders). The markings on the underside of the body of hobos have a light tan center with dark bands on the sides where the legs join (while domestic and giant spiders have small circles on the sides). Domestic spiders are observed around all year while most encounters with hobo spiders will occur in late summer and fall (hobo mating season). Hobo spiders really do prefer to be outside in meadows and wood piles. Occasionally, webs and egg cases will be constructed inside basements or crawlspaces. These webs are recognized by the characteristic funnel shape. Egg cases will be made during the fall through November. All spiders are venomous and therefore should be handled with caution. They use their venom as a means of prey capture and not defense, unlike bees and wasps. As of yet, hobo spider bites are not fatal. Most bites occur starting in August and September when males are out of their hiding places seeking females with which to mate. The severity of a bite is about as variable as people are. It is believed that up to one half of the bites by hobo spiders are ‘dry bites’ meaning that no venom is secreted. Bites can affect someone directly (meaning that the bite area shows evidence of a bite) or systematically (like an allergic reaction). Hobo spider bites can directly cause skin necrosis. At first, the bite may appear as a mosquito bite which will then blister. After blistering, the lesion will ulcerate and possibly turn black as the tissue dies. This is common in areas where the skin is soft. Depending on the severity of the bite and the individual’s reaction to it, the wound may heal in a month or two years. Systematic reactions include allergy symptoms such as nausea, fever, headaches and joint soreness. It is very important if you are bitten by a spider that you collect the spider and get it identified correctly. Identification will help physicians react to the injury appropriately. For in-house encounters, simply barricade the area that the spiders are using to get in. Sticky traps are quite effective in areas where many spiders are entering. For large infestations under the house or in basements, chemical control may be a consideration. When moving any debris or wood outside, wear protective clothing and gloves. This is also very important when venturing into areas of known infestations such as the crawl space. Be sure to check your gloves and shoes before you put them on. Finally, the best and most long-term solution is to let nature take its course. In Europe, where all three species of house spiders come from, the hobo is not a problem inside the house. The hobo spider was introduced prior to the giant house spider. Now the giant spider population is increasing, while the hobo spider is decreasing in frequency of occurrence. As a result, the number of bites in the household is decreasing. The giant spider is a fierce competitor of the hobo spider and will keep hobos out of its territory. In addition, the giant house spider is relatively harmless and bites are rare. This is why hobos are not a problem in Europe: they are naturally controlled.