How to Tell It's NOT a Brown Recluse

Just Because It's Brown Doesn't Mean It's a Recluse

This brown recluse or violin spider (Loxosceles reclusa) is a species of spider native to North America
Ladyb695/Wikimedia Commons/CC BY-SA 3.0

To identify a brown recluse spider you need a very strong microscope and a spider expert.

And an actual brown recluse, which might be harder to find than you think.

These guys are tough to identify even by the experts. Unless you actually have a specimen to analyze, there's no way to know what it was that bit you or that scurried across the kitchen floor. It takes close examination of the spider itself to rule out all the other potential species that look like a brown recluse but don't pack nearly the same punch.

Likewise, you can't tell a brown recluse bite by the wound. There's no blood test or culture that can show presence of brown recluse venom in a suspected spider bite. There's no classically reliable pattern of signs or symptoms to help pinpoint this particular species.

If anything, identifying a brown recluse is more about ruling out what it isn't rather than figuring out what it is. I can't really help an amateur arachnologist identify a brown recluse, but using these steps I can help you figure out the other 99% of the time when it's not.

First, we start with where you found the spider.

Did You Find Your Spider in Known Brown Recluse Territory?

brown recluse distribution map
Known habitats of loxosceles species. (c) Rick Vetter

Brown recluse spiders live in a well-defined area in the southeastern part of the United States. Within their habitat, they're hard to find. They are called "recluse" for a reason: they don't like to play with others. These spiders like dark, dingy places. They hide under things and prefer living where the sun don't shine.

Inside their habitat, brown recluse spiders cause serious infestations. Where there is one, there are most likely dozens or even hundreds. However, even in homes with such outrageous infestations, bites are very rare.

The scientific name for the brown recluse is loxosceles reclusa. In all those other colored areas of the map are other loxosceles species (Texan recluse, desert recluse, etc). They're related to the brown recluse and all have similar venom. Indeed, some of the other loxesceles species have worse venom than the brown recluse.

So, if the spider was found outside of the known habitat of a brown recluse, then it is almost certainly not a brown recluse. Outside the other areas means it's not even related to the brown recluse. If you have a specimen from inside the brown recluse zone (or if you think the experts are wrong about your particular spider even though you aren't in brown recluse territory) then let's try to figure out if it's not a brown recluse.

Let's take a look at its legs.

Loxosceles Rhymes with Isosceles for a Reason

brown recluse legs
The legs of loxosceles are slanted -- it's what the name means.. Image courtesy of CDC

Loxosceles rhymes with with isosceles, which you may remember from geometry is a type of triangle. The words are similar for a reason.

Loxosceles actually means slanted legs. If you look at a brown recluse from the side you can see how the body sits low and the legs angle up to a point. It's that angular, slanted shape of its legs that give the brown recluse its scientific name.

Two more distinct features of brown recluse legs:

  • No spines: Unlike many other spider species, loxosceles does not have spikes or spines on its legs. They are smooth.
  • One color: Some spiders have multi-colored legs, but loxosceles keeps it solid -- no stripes and no patterns.

If your spider doesn't have these legs then it's definitely not a brown recluse. If you find these leg characteristics similar to your spider then look into its eyes, all 6 of them.

It's Watching You: The Eyes of the Brown Recluse

eyes of brown recluse versus other spider species
The most important identifying characteristic of brown recluse spiders is their eyes.. Top images (c) flickr user aviplot. Bottom image courtesy of CDC

Assuming you're in brown recluse country and you have a spider with a low-slung body on angled, smooth, solid color legs, the next thing is to look your spider in the eye.

Brown recluse spiders have 6 eyes. They're paired in what are known as diads and arranged on the front and sides of the brown recluse's head (see image upper left and bottom). Other spider species might have 8 eyes or they might have 6 eyes arranged in two triads (groups of three).

These guys are tiny, so seeing their eyes without a microscope is going to be difficult. If you have trouble with the fine print like me, you'll probably at least want a magnifying glass.

You can't be sure if it is a brown recluse based only on the eyes, but if the eyes aren't in the proper pattern then it's definitely not a brown recluse.

You got here because your spider had smooth, angled legs of all one color and you found it in brown recluse territory. Does your spider also have the proper peepers? If not, you're done here. If it does, move on to the rest of the body.

If the Legs and the Eyes Look Good, How About the Rest of the Body?

brown recluse compared to a penny
A penny shows just how small a brown recluse is.. (c) Kurt Nordstrom

There are two more characteristics you need to see for this to be a loxosceles:

  • The body (without legs) has to be small, no more than 3/8 of an inch.
  • The abdomen (big round part on the backside) needs to be a little fuzzy with very fine hairs and a solid color.

Brown recluses are boring when it comes to fashion. They like solids. They aren't into patterns or stripes and that is obvious on their legs and abdomens. There is one common brown recluse fashion statement that everyone seems to know about: the fiddles on their backs.

Isn't It Called a Fiddleback for a Reason?

desert recluse
The classic violin mark isn't obvious on all species of loxosceles like this desert recluse, but the venom is just as bad.. (c) Marshal Hedin

The one feature most commonly talked about in brown recluse descriptions is the violin shaped mark on its back. I've seen what folks are talking about and I never thought it was much of a violin shape. It looks more like a spatula to me, but maybe that's because I cook and I don't play the fiddle.

Not all loxosceles are brown recluses, but they all have similar venom. Not all brown recluses have the classic violin mark. Even if it's there, you might not be able to clearly see it.

Worse yet, there are a bunch of spiders that also have the violin marking on their backs and they're not brown recluses. In many cases, they're not even venemous to humans. The worst case scenario is that a doctor thinks you've been bitten by a brown recluse when you have not. There's no antivenin -- no specific treatment -- for brown recluse bites, but many wounds that are diagnosed as brown recluse bites are actually infections and could be treated with antibiotics as long as your doc diagnosis it correctly.

Counting on the fiddle to identify a brown recluse is a bad idea.


Vetter, RS. "Brown Recluse and Other Recluse Spiders." UC IPM Online. Revised Jan 2008.

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