PPDL Picture of the Week for
November 5, 2012

Brown Recluse Spiders Don't Crawl Up The Water Spout

Timothy J Gibb, Insect Diagnostician, Department of Entomology, Purdue University

Our local TV channel did a story about a woman who had been bitten by a brown recluse spider and was in the hospital because of it. Since then we have received several questions and concerns about brown recluse spiders.

Although we have always had brown recluse spiders in our state, it is not a common spider. They are generally encountered indoors, particularly in bathrooms, bedrooms, closets, garages, basements, and cellars and most often where clutter is present. As its name suggests, the spider is 'reclusive' and is shies away from places where there is a lot of activity. Guest bedrooms and basement areas that don't often have people in them are likely spots where the spider will live. The spider is not aggressive and will usually retreat to cover if disturbed.

Most spiders are beneficial because they eat other insects that could become pests. A brown recluse spider is one of the 1% that can actually be harmful to people.

It is important to identify the spider in question and especially if your think that it may have bitten someone. Capturing the spider in a bottle or jar is one way of holding it for positive identification.

Many spiders are similar in size color and shape to the brown recluse spider and many even have dark markings on their backs, however, to identify a brown recluse, remember that it’s body measures from 1/3 to 1/2 inch in length. If it spreads out its 8 legs, the spider will easily cover a 1 inch diameter circle. It’s color varies from yellow to dark-brown and has the distinctive and characteristic darker brown violin-shaped mark on the top of its back.

If a spider does not fit this description, it is not a brown recluse.

Most bites occur while putting on old clothes that have been hanging for a time in a garage or basement, by rolling on a spider in a guest bedroom during the night, or by picking up a box and inadvertently trapping a spider with a hand or arm. Out of self-defense, the spider will bite and inject its toxin.

The pain from the spider bite usually is not intense at first, only resembling a small bee sting. However, within 8 - 12 hours the pain typically becomes very intense and over a period of a few days, a large ulcerous sore can form.This sore heals very slowly and may sometimes require skin grafts. In most cases, a large, ugly disfiguring scar will be left. Danger from the bite primarily depends upon two factors; the location of the bite and the susceptibility of the victim. Children and the elderly are especially at risk.

Avoid being bitten by learning to recognize brown recluse spiders, remember how they behave and where they live. Despite their fierce reputation, brown recluse spiders do not appear overly large, intimidating, or aggressive, nor are they prone to crawl up the water spout.

Click image to enlarge

Brown recluse

Close up of back of brown recluse

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service