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The Tegenaria agrestis or the Hobo Spider

Keep Voles from Damaging Your Young Trees

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By Ron Thaemert, Extension Educator – Crops, Blaine County Extension Educator

(Note the brown legs with no spots or stripes and the abdomen with a mottled pattern.)

This large spider, indigenous to Western Europe, was introduced into the northwestern United States (Port of Seattle) sometime before the 1930’s.  The means of introduction into the United States was almost certainly by commercial shipping vessels carrying agricultural cargo from Europe.  It is highly improbable that the hobo spider arrived as a mobile organism, but rather migrated to the United States as egg cases attached to wood or some other type of storage container.

In Europe, the hobo spider is a resident of more rural areas, rarely entering human habitations due to the presence of major competitors, particularly the giant house spider.  Upon the arrival to the United States, the hobo spider rapidly adapted to living in urban areas and, without the widespread presence of a dominant competitor, it thrived and began extending its range.

Between the two front legs, the male hobo spider sports two pedipalps (antennae like protuberances) that are swollen at the ends, looking similar to a pair of boxing gloves.  These “boxing gloves” are actually the male genitalia, not “fangs” or “poison sacs”.  The female generally has a larger abdomen than the male, and does not have the swollen ends on the pedipalps.

In case of a spider bite, it is very important to obtain a positive identification of the spider from a qualified professional. The accurate diagnosis and treatment of tegenarism (hobo spider poisoning) is relatively new and presents a challenge to physicians and other health care workers.

Prevention of the hobo spider bite is much easier to deal with than the treatment for a bite.  Use simple common sense measures to prevent bites.  Hobo spiders are not good climbers, and are usually found at ground or basement levels.  To climb, the hobo must locate a porous surface.  They can fall easily and will be seen stuck in slick surfaced areas such as wash basins and bathtubs.

Keep bedspreads at least eight inches above the floor and keep beds at least eight inches from porous wall surfaces.  These measures will minimize the possibility of unwelcome biting eight-legged bed partners.

Protective clothing (e.g. coveralls tucked into boots and long sleeves tucked into gloves) should be worn to cover bare skin when working in enclosed infested areas such as crawl spaces, rock gardens, and old piles of wood.  Indoors, shake clothing out that has been stored or laid down in spider inhabited dwellings.  Routine thorough household cleaning can reduce spider populations, making certain to vacuum thoroughly in corners, in closets, behind furniture, and underneath beds 

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Keep Voles from Damaging Your Young Trees 

By Jo Ann Robbins, Extension Educator - Crops and Horticulture, Jerome County

How do voles damage trees?

            Voles can cause extensive damage to small trees.  They girdle the bark at the base of the tree, around the root collar, and along the major feeder roots.  These girdled areas can weaken trees and serve as points of infection for various rots.  When trees are severely damaged they will die.

             A young tree has a limited amount of bark and a few voles can readily girdle it.  Voles also prefer the relatively soft and succulent young or inner bark.  Young trees are therefore very susceptible to damage by voles.

 Clean cultivation helps reduce vole damage.

            To protect your tree you can keep the area around the tree clean-cultivated.  This will deprive the voles of protection and a food source.  Eliminate all vegetation next to the tree base.  A 3-foot strip or circle is recommended at the minimum.  Cultivate or spray with an approved herbicide.  Remove all dead material.

 Provide trunk protection.

            A physical barrier may be made to protect trees by encircling the trunk with a vole guard.  Guards may be made or purchased commercially in a variety of designs.  Materials include metal, plastic, fiberboard, and other products.  One common material is wire screen cut to form a cylinder around the tree trunk that is secured loosely with short strands of wire.  Regardless of the material used, it is important that the guard be of sufficient height and length to protect not only the trunk, but also the surface feeder roots.  It is helpful to bury the bottom of the guard 2 or 3 inches below ground to prevent voles from crawling under it.

 Poisons and traps

            Poisons can be purchased to kill voles.  Most of those that can be used by the homeowner can cause problems with pets if they consume a number of voles that have been killed by the poison chemicals.  To be effective, poisons must be widely distributed prior to a population explosion.  Traps will also reduce the population.  These techniques can help to lessen vole problems and are most effective early in the season to keep the vole population from increasing.

 The bottom line

            Clean cultivation and vole barriers are recommended in areas of high vole populations.  In such areas poisons and traps can never be effective in completely reducing the possibility that your new trees will be damaged by voles.

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This page was last updated on :    29 April, 2009