How to Identify Spiders in Eastern Oregon

Telling one spider from another can be a confusing task, especially when all that's on your mind is how to avoid getting bit. But in Eastern Oregon, the distinction is fairly simple. There are two varieties of poisonous spiders in Oregon: the Hobo (or Aggressive House) spider and the Black Widow. Here's how to tell if the spider you have found is one of these two venomous spiders or one of the many varieties of harmless spiders that resemble them.

Things You'll Need

  • Magnifying glass
  • Notebook
  • Pen or pencil
  • Field guide (optional)
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Instructions

    • 1

      Take note of the size and shape of the spider. Oregon spiders can be as small as a pencil eraser or almost as large as a compact disc. Black Widows, the most venomous of Oregon spiders, is relatively small, with a bulbous abdomen and compact design. Hobo spiders, poisonous relatives of other types of house spiders, can be as wide as half an inch or larger, with widely placed legs. The harmless domestic and giant house spiders are sometimes confused as Hobo spiders, but they have subtle differences.

    • 2

      Look carefully at the color and markings of the spider. Brown is a very common color for spiders, and can lead to confusion when trying to make a final identification. However, each spider has different markings, and besides some small exceptions, can be identified in this way. Female black widow spiders are easy to identify with the red hourglass shape on a black abdomen, although you shouldn't be surprised to see white or orange markings on some widow spiders. Males in particular have a yellow or brown stripe down the back with white or yellow streaks. Hobo spiders do not have rings around their legs as the other domestic house spiders do. Instead, they sport Chevron-shaped markings on their abdomen. Wolf spiders are grey or tan with striped patterns on their backs, often referred to as Union Jack impressions.

    • 3

      Look for a web. Although webs are synonymous with spiders, not all spiders use a web to capture their prey. The webs of Hobo spiders are easily recognized as funnel-shaped, often attached to outdoor furniture or other stationary objects close to the ground. Similarly, house spiders also make such webs; however, the jumping spider for one, doesn't weave a web but pounces on its prey. These are easily distinguished by its jerky movements and obvious jumps from one spot to another. The Wolf Spider doesn't use a web at all, but preys on its victims.

    • 4

      Use a magnifying glass to get a close-up of the spider's "face" or eyes. If the eyes are evenly placed in two rows of four eyes, you are not dealing with a venomous spider. Wolf spiders, jumping spiders, and hobo spiders have eyes arranged in an uneven pattern, with eyes arranged in a 4, 2, and 2 pattern over three rows. If you can see the underside of the spider, you will find a difference between Hobo spiders and their nonvenomous cousins, the Domestic and giant house spider. A Hobo's cephlothorax (the head and thorax together) has a light tan center with dark bands where the legs join, while the domestic and giant spiders have small circles there.