Entomology - Spiders

Updated Jan 2005 

Because of media hyperbole and anxiety-filled stories by the general public extolling the horrors associated with brown recluse spiders, people are very interested in knowing if the spiders they find are brown recluses.   Although it is true that a brown recluse has a violin pattern, many non-arachnologists creatively misinterpret many markings on spiders as "violins" and feel that they have found recluse spiders.  Therefore, if you can learn to identify your spider as NOT a recluse, you can relieve your worries.  You won't be able to tell what it is (and please don't send them to me for identification because due to shift in the California economy, I no longer provide these services) but you will at least know that it is not a recluse spider. 

Several important things:

1- check the map at spiders.ucr.edu/images/colorloxmap.gif to see if you live in an area that is supposed to have recluse spiders.  If you do not live in any of the colored areas in the map, then it is HIGHLY UNLIKELY that you have a recluse spider.  It is POSSIBLE but incredibly unlikely. 

2- because so many people have mistaken markings on a spider as violins, this is NOT a reliable characteristic for a non-arachnologist.  You need to look at the eye pattern.   

3- even if you have a recluse, bites from them are extremely rare, despite all the stories.    Many of the really graphic nasty wounds you see on the internet as recluse bites can also be other conditions like necrotizing bacteria and pyoderma gangrenosum.  Ninety percent of brown recluse bites are not medically significant, heal very nicely often without medical. intervention and treatment for most brown recluse bites is simple first aid (RICE therapy - Rest, Ice, Compression, Elevation).  Many conditions are misdiagnosed as recluse bites when their cause is something else like infection, bad reaction to medication, diabetic ulcers, Lyme disease, or other underlying medical conditions.

What does a brown recluse look like? 

A brown recluse has a dark brown violin shape on the cephalothorax (the portion of the body to which the legs attach).  The neck of the violin points backward toward the abdomen.  However, what you should look at instead is the eye pattern of 6 eyes in pairs with a space separating the pairs.  Most spiders have 8 eyes in two rows of four.

Here are the things that describe a brown recluse spider (but some other spiders have a few of these characters too).  There are pictures below to illustrate what is NOT a recluse.

1. Six eyes arranged in pairs, with one pair in front and a pair on either side.
2. A dark violin shape on the cephalothorax.
3. Uniformly light-colored legs - no stripes, no bands
4. Uniformly colored abdomen which can vary from cream to dark brown depending on what it has eaten, however, it will never have two colors of pigment at the same time.  (The little discoloration on the spider above left is the heart which can be seen through the thin skin.)
5. No spines on the legs, only fine hairs
6. Recluses make small retreat webs behind objects, never out in the open.
7. It is about 3/8 of an inch in body length.

 All of the specimens shown below have been submitted to me as brown recluses!!!!!!  None of the spiders below should be considered dangerous. 

Six eyes, not eight

            You may not always be able to count the eyes and some eye pairs are so close together that you might not be able to see both of them, however, the 6 eye pattern of the brown recluse is easy to see with minor magnification.  Most spiders can be eliminated as NOT brown recluses simply from this aspect.  Be aware that there are spitting spiders (genus Scytodes) (below) which have a similar eye pattern but they do NOT have a violin (plus it has more than one color on its legs and abdomen).

 Dark violin pattern

            People have submitted the following spiders because they thought that they saw violins on their bodies.  People also claim to see the violins on the top and bottom of the abdomen, and the underside of the cephalothorax. In the left photo, the two light spiders look like they have violins but they also have 8 eyes (although you need a microscope to see all 8 of them) and more than one pigment on the abdomen so they are not recluses (they are cellar spiders, genus Psilochorus and/or Physocyclus).  The other spider in the left picture has a very faint dark line pattern which people assume is a violin.  It also has 8 eyes and massive spines on its legs, so it is not a recluse.  In the right photo, this spider has a slight darkening near its eyes so people mistake this for a recluse violin.  This spider has 8 eyes clumped together and black spines on its legs although you may not be able to see the spines in this image (genus Kukulcania).

Uniformly colored legs and uniformly colored abdomen

            If there is more than one color on the legs, or if the legs are brown or darker, it is NOT a recluse.  If the spider has more than one pigment on the abdomen, it is NOT a recluse.  The top two spiders are funnel weavers (family Agelenidae), the bottom left is an orbweaver (family Araneidae), and the bottom right spider is a male huntsman spider (Heteropoda venatoria) found most often in Florida but occasionally in other gulf coast states.  They are can be determined to be NOT recluses by more than one color on their legs or abdomens.

Fine hairs only, no spines

            If the spider has conspicuous thick spines on the legs, it is NOT a recluse. This orb weaver below has many spines sticking out perpendicularly from the legs.

 Web made out of sight

            If the spider has a conspicuous web out where you can see it, or between two trees or in rose bushes, it is NOT a recluse.  The "classic" spider webs like that of Charlotte's Web are made by orb weavers.

Not larger than 1/2 inch in body length

            If the spider has a body length of greater than half an inch, it is NOT a recluse.