If you live on the east coast, the west coast, or in any of those big square states, you almost certainly did not see a deadly brown recluse in your basement that one time. If you know somebody who was bitten by one, there’s a good chance they weren’t . Even within the recluse’s territory, chances are still low.
Part of the confusion is because a genuine brown recluse is so unassuming. We all know a black widow when we see one: black with a roundish abdomen, and countless cartoons have taught us to look for a red hourglass on its belly (if we dare to get so close). But the brown recluse’s main characteristic is that it is, well, brown. Here’s a hot tip: lots of spiders are brown.
Actual brown recluse spiders, Loxosceles reclusa, live in the southern US, in the area shown on the map below.
The top map is a good rule of thumb; the four lower maps are from in-depth studies aiming to get specific about the range. They were collected in a study published in PLOS ONE that concludes, later in the paper, that brown recluses are likely to move northward with climate change. South Dakota, Michigan, New York, and parts of New England could get their own brown recluse populations as soon as 2020, while Texas could end up recluse-free.
But for now, a lot of spiders and spider bites are misidentified. A real brown recluse, according to spider expert Rick Vetter, has these features:
Just being brown doesn’t cut it. Nor does the violin shape alone, because a lot of spiders have violin-like marks. You’ve got to gaze into that little critter’s eyes, and count them. Most other spiders have eight eyes, in two rows of four.
Still stumped? Tweet a photo to @RecluseOrNot on Twitter, and spider experts will help you out. They see plenty of daddy long legs, cellar spiders, hobo spiders, and wolf spiders—which are big and hairy and you are 100 percent justified in screaming a little if one sneaks up on you.