Brown Recluse Spiders

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We get a lot of random things brought into our office for identification. Grasses, trees, flowers, snakes and insects all commonly make their way through our door. You never know what might come into the office on any given day! Recently, the most commonly brought in living (or once living) creature has been the brown recluse spider.

Unfortunately, we live in an area where they are extremely common. Brown recluse spiders feed on other insects and like to live in quiet, dark areas that don’t see a lot of human activity. Our climate and lush vegetation mean that we have a great habitat for insect populations of all kinds, meaning that we have a great food source for brown recluse spiders. And our attics, closets and basements are all great places for a spider to take refuge when the weather shifts.

Brown recluse spiders are one of two native venomous spiders in the state of Kansas. The other is the black widow, which isn’t as common in Johnson County. Because the brown recluse is venomous, we need to take some extra precautions when dealing with them. Just like allergies, some people react more to their bites than others. If you know, or suspect, that you have been bitten, it is important to see your doctor.

Knowing how to identify a brown recluse spider is your first step to knowing if you have a problem. They are generally brown in color and have slender legs with defined structure and pattern. On the back is the classic ‘violin’ shape, though a few other species of spiders have the violin shape on them as well. The number one characteristic to confirm an identification is to take a look at their eyes under a hand lens. Brown recluse spiders have three sets of two eyes each. The attached publication from K-State Research & Extension (KSRE) has some great photos for comparison.

Once you have found a brown recluse spider in your home, I would suggest utilizing foldable sticky traps. Place traps in a closet, basement, attic or other locations that are dark and don’t see much human foot traffic. Check these traps regularly to see if any other brown recluse spiders show up. Remember, they feed on insects, so the other insects that become trapped will then be bait.

One of the best ways to keep your home from becoming a home to these spiders is to make sure that other insect populations are kept to a minimum. Make sure that your window sills and door jams are sealed tight. Any holes or gaps in your foundation can be an entrance for insects into your home, and the brown recluse spiders that feed on them.

Studies have shown that brown recluse spiders are not consistently controlled by pesticides, so do-it-yourself home insecticide treatments aren’t proven to be successful. Eliminating their food source, however, is a way to eliminate an infestation over time. If your home has been treated by an insecticide for other insects, it is good practice to go through the home and do a thorough cleaning. All dead insects need to be removed so that they are not seen as a food source.

Sticky traps may be slow and more of a reactive treatment, but it will keep them from coming into contact and leaving a bite. Another way to prevent bites is to not leave clothing or towels laying on the floor. Remember, they love dark spaces and a hoodie or shirt on the ground is a perfect hiding place. Shake out any clothing before putting it on will help minimize risk of bites.

See the publication on brown recluse spiders from KSRE for more information and helpful pictures in identification. https://www.bookstore.ksre.ksu.edu/pubs/mf3133.pdf

Contact Us

Amy Keigher

Natural Resources Agent
amy.keigher@jocogov.org
913-715-7000