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How to identify (or misidentify) the hobo spider Rick Vetter 1 and Art Antonelli 2
Since the late 1980s, many people in Washington have been concerned about the hobo spider because it has been blamed as the cause of dermatologic wounds. We offer here a guide to help identify some medium-sized Washington spiders found in homes. However, keep in mind that without a microscope you may not be able to identify hobo spiders and may have to settle for determining that your spider is NOT a hobo spider. This may be frustrating and not the goal you had in mind, however, quite often the question is not "What spider do I have?" but "Do I have a hobo spider?" You should be able to learn ...view middle of the document...
because of the insects they eat. What this publication tries to do is Fig. 1 Hobo spider Photo by P. K. Visscher © 1 Dept. Entomology, Univ. Calif. Riverside, CA 92521 2 Extension Specialist, Wash. St. Univ., Puyallup, WA 98371
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A general warning Most non-arachnologists try to use coloration as a diagnostic identifying feature. This is one of the least reliable characteristics for identification of hobo spiders because of the great variation amongst specimens within a species and because similar species sometimes overlap in their appearance with hobos. If you try to identify them by size, you will also be mistaken because the variation is tremendous. Many other species look the same to the non-arachnologist who lumps them all together as hobo spiders and often is wrong. If you continue to try to determine spiders with coloration or size, then this publication is not going to help you. You must be willing to take your skills above the level of the non- arachnologist, learn a few anatomical structures and then you will have better success. As an analogy from the world of ornithology, it is easy to determine an eagle from an owl, etc. but it takes much more skill and effort to differentiate amongst the many species of similar-looking warblers. Thus, it is the same for the hobo spider and many of the medium-sized Washington spiders. You will need to be more discriminating when dealing with hobo spiders because identification is not easy. This guide is geared toward the interested reader who has a magnifying lens or hand lens, similar to what Master Gardeners or entomologists would use. Yet even with a lens, quite often you may be able to determine that your spider is NOT a hobo spider and nothing more.
For the few who have access to microscopes we present information on how to definitively identify hobo spiders to species. For the advanced beginner, this can only be reliably achieved by comparing the male and female reproductive structures to the pictures presented here. If you are able to do this, you can learn the skills of an amateur arachnologist and can determine without a doubt whether or not you are in possession of a hobo spider.
We present mostly identification information here. If you wish to learn the biology or other aspects, you should check out the references at the end of the article. A little bit about the spiders The hobo spider is found throughout Washington and makes a funnel web which is a trampoline-like flat sheet leading back into a hole between bricks, under wood or in shrubs. However, there are many closely related species of spiders which also make similar webs so just because you see funnel webs on your property, does not mean that there are hobo spiders in those webs.
The scientific name of the hobo spider is Tegenaria agrestis. Also living in Washington are 2 other closely related spiders, the giant house spider, Tegenaria duellica (known as Tegenaria gigantea to some) and the barn funnel weaving...