Harney County is home to two poisonous arachnids
By Randy Parks
Burns Times-Herald
It may not reach the level of arachnophobia, but most people seem to have an aversion to spiders.
Although most spiders in Harney County are relatively harmless, there are two spiders in our area which cause some concern; the black widow and the hobo spider.
Black widows are fairly easy to distinguish with their shiny black body and a red hourglass marking on the underside of their abdomen.
The hobo spiders however, are not so easy to identify as they share characteristics with many other spiders.
Jim Nelson, who lives on South Kearney in Burns, found funnel-shaped webs around his home and later noticed a spider running across his living room floor. He was able to trap the spider in a glass jar and showed it to a neighbor. “He told me, ‘Congratulations Jim, you’ve caught yourself a hobo spider,’ ” Nelson said.
Using a magnifying glass, Nelson examined the markings of the spider he caught and compared them with with pictures of the hobo spider he found on the Internet.Nelson has since caught more spiders and identified them as male and female hobos. “If they mate and lay eggs, that could mean anywhere from 100 to 300 babies in the spring,” Nelson said. “That concerns me.”
While Nelson is sure that the spiders are hobos, positive identification should be made by an expert. Harney County Extension Agent Dustin Johnson said, “You can’t tell just by looking at them because they all vary in how they look. The only sure way is to have an expert dissect them.”
Johnson said that if a resident is wondering if a spider is a hobo, they should kill it in an alcohol solution and bring it to his office in the Harney County Courthouse. “We’ll send it off to Oregon State University (OSU) for identification,” he said.
Johnson stated that he did have a resident bring him a spider this summer, and it was confirmed as a hobo by OSU experts.
The hobo spider
The hobo spider is also known as the aggressive house spider, which is a bit of a misnomer as they are not really aggressive.
They do build a funnel-shaped web, which is non-sticky, and when an insect lands on the web, the hobo uses its speed to quickly move in on the prey.
They have been known to bite humans, but many Web sites report that 50 percent of the bites are “dry,” or contain no venom.
Although the bite of the hobo spider is painless at first, the bite can be serious.
The Web site www.ter mite.com reports, “After 24 hours, the bite develops into a blister and after 24-36 hours, the blister breaks open, leaving an open, oozing ulceration. Typically when the venom is injected, the victim will experience an immediate redness, which develops around the bite. The most common reported symptom is severe headache. Other symptoms can include nausea, weakness, fatigue, temporary memory loss and vision impairment. In any case, first aid and medical attention should be sought, if bitten, when any adverse health effects are observed.”
The hobo is one of three closely related species of house spiders found in the Northwest. The three species include the domestic house spider, Tegenaria domestica, the giant house spider, T. gigantea, and the hobo spider, T. agrestis.
According to the Web site whatcom.wsu.edu, “The domestic spider is the most commonly encountered spider in your house and is the smallest spider of the three (less than a 1/2 inch in body length). The giant house spider will usually be obvious, these spiders are huge! Generally, the hobo spider is medium to medium large. The body alone can be up to 3/4 of an inch in length in mature adults.”
This site also cautions against trying to make a positive identification as “when identifying these spiders, there are always exceptions to the rule.”
Avoiding the bite
The hobos aren’t vertical climbers, so their webs will most often be low to the ground, nestled between rocks, wood or other objects, which aren’t often moved.
As Nelson took a walk around the outside of his home, he pointed out a number of ideal sites for a web. “That rock pile right there, cracks in the foundation, a railroad tie, pallets, they’re all perfect for the hobo,” he said.
Wearing long-sleeve shirts and gloves while working around these areas can help prevent being bit.
People have also reportedly been bitten when they rolled over on to a hobo in bed or put on clothing or shoes which had been on or near the floor.
Some experts say the the best and most long-term solution (but probably the most undesirable) 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 to the United States 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 spider is relatively harmless and bites are rare. This is why hobos are not a problem in Europe — they are naturally controlled. The giant spiders are the good guys in this case, so the next time you see one, rather than splat him against the wall, give him a pass.









