Utah Pests News Summer 2007

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Hobo Spider Sightings in Utah



Hobo spiders build prey-catching funnels along foundation cracks or wood piles.

The hobo spider was first detected in the United States in the 1930s and was restricted to the Pacific Northwest for many years. But eventually the hobo spider was detected in Utah in 1990 and since has been reported in about half of all counties (Box Elder, Cache, Davis, Morgan, Salt Lake, San Juan, Sanpete, Summit, Tooele, Utah, Wasatch, and Weber). Several hobo spiders have already been submitted to the Utah Plant Pest Diagnostic Laboratory in 2007. This time of year, most specimens are captured indoors, particularly in basements.

The hobo spider is a member of the funnel-web spider family Agelenidae. Members of this spider family typically have long legs and are considered swift runners compared to other spiders. Unlike other spiders, the hobo spider is a poor climber and is generally seen on the floor. As with many spiders, identification of the hobo spider is very difficult and requires a trained eye. With the passing of Alan Roe in 2006, the UPPDL lost an expert in spider identification. But we do have other entomologists in the UPPDL and Biology Department who are available for spider diagnostics.

Hobo spiders can cause a painful bite resulting in a necrotic lesion. Although the hobo spider is not more aggressive than other spiders, they will attempt to bite in defense. Sometimes hobo spiders deliver a "dry" bite and no ill effects are suffered. However a full envenomation will often cause burning, swelling and blistering of the skin. A severe bite can take several weeks to several months to heal and will most likely leave a scar.

To reduce the risk of getting a spider bite, prevent spiders from entering the home. Seal cracks, crevices, or other openings around buildings and other structures. Cleaning debris, such as weeds or wood piles, around the perimeter of a building will also discourage spiders from accidental introduction indoors. Traps can be useful for detecting and controlling hobo spider in the home. Consider using commercial sticky traps designed for rodent or insect control. Traps should be placed along baseboards or in other areas where the spiders are seen.

To find out more about the biology, life cycle, and other control options for hobo spiders, visit our Web site. We have recently revised the hobo spider fact sheet. Do not hesitate to send spider samples to your local county extension office or the UPPDL for confirmation.

-Erin Hodgson, Extension Entomologist