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Brown Recluse Spiders

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Spiders are feared and reviled, more so than even the most dangerous of insects. While having eight legs isn’t helping their creepiness factor, spiders are mainly feared for their venomous nature. Almost all spiders have venom, but only a few have venom potent enough to harm humans.

In the South, the brown recluse is the most dreaded of them all – I know because I get a lot of brown spiders brought to me with concerns that they might be brown recluse! Unlike black widows which are easily identified by the public, the brown recluse is rather unremarkable in shape and color, and many other spiders share similar characteristics. Lots of spiders are brown, slender, leggy, and run along the ground. Plus, most people only get a glimpse of a quick-moving spider, and they assume the worst.

The brown recluse is problematic because it can live and breed indoors. It particularly loves attics and garages, especially if they are filled with clutter and cardboard boxes. A spider needs to eat, and it prefers small, soft-bodied insects. Controlling silverfish, crickets, and other similar pests will prevent your brown recluse from indulging in an all-you-can-eat bug buffet. Brown recluse populations cannot explode without a consistent food supply.

If you’ve done an Internet search for brown recluse spider bites, then I’m sure you’re terrified now even if you weren’t before. But most of those wounds aren’t from brown recluse bites. A medical professional cannot positively diagnose a brown recluse spider bite from a wound alone. There must be a spider to accompany it to be certain. Staph infections, diabetic issues, herpes, and a whole host of other diseases cause slow-healing ulcers with tissue death. That’s not to downplay the medical importance of the brown recluse spider – it has cytotoxic venom which can cause necrotizing bite wounds, slow healing, and significant scarring. It is estimated that less than 10% of bites result in complications. The other 90% of bites heal normally. Anyone who has reacted severely to the bite of a brown recluse once is likely to have a similar reaction again. No one can predict if a bite will be severe or not for someone who has never been bitten before. Sometimes a spider will dry bite and not inject any venom, other times a spider will bite and inject all the venom it has stored up. Death is extremely rare: less than 1% of bites results in a severe, systemic reaction that can cause kidney failure, low blood pressure, and the breakdown of red blood cells.

If you must work in areas with brown recluse spiders (i.e. moving boxes around in the attic), wear leather gloves to protect yourself should you accidentally pinch a spider against your skin. If you ever get bitten by a spider, catch the spider so it can be identified.

Telling the difference between a brown recluse and other brown spiders

The brown recluse is somewhat unique among spiders in that it only has six eyes – most spiders have eight. The six eyes are arranged in pairs of two in a semicircle at the front of the face. You may need a hand lens to see the eyes. A few other spider groups have six eyes arranged in this pattern, but they don’t look anything like a brown recluse.

Sometimes called fiddleback spiders, the brown recluse has a distinctive violin-shaped marking on the head-region of its body. In some specimens it is very pronounced, in others it is more subdued. Many other spiders have vague, violin-like markings, so it’s wise to look at more than just the markings when making a determination.

The legs are uniform in color with no markings, stripes, or bands. Look-alike spiders, like the male crevice weaver, will have spines on their legs but the brown recluse will not. The brown recluse may have fine hairs, but never any spines.

The abdomen is smooth and velvety in appearance with no markings. Wolf spiders are often misidentified as brown recluse spiders, but they usually have stripes or other patterns on their bodies and abdomens.

When in doubt, have a professional pest control company identify your spiders.

References:
Elbahlawan LM, et al. 2005. Severe systemic reaction to Loxosceles reclusa spider bites in pediatric population. Pediatr Emerg Care 21 (3): 177-80. Accessed via PubMed: https://www.ncbi.nlm.nih.gov/pubmed/15744197.