Brown recluse spiders (June 6, 2013)

Guest Post by Sydney Glass, Integrated Pest Management Intern.

The insect of the week is the Brown Recluse. The brown recluse has many other names such as the violin spider, the brown fiddler, and fiddleback spider. The brown recluse is very dangerous, and if bitten seek medical attention immediately.

APPEARANCE:

The brown recluse is normally 6-20mm in length (or about ¼ in – ¾ in) but it can grow larger. The color of the Brown recluse varies from a light shade of brown to a dark brown or black-grey. Often, the bottom section of the spider is not the same color as the top section. Brown recluse usually looks smooth and hairless. Usually, an indicator of identifying a brown recluse is by looking at the top of the body where there should be a violin looking shape on the cephalothorax (head + thorax - the front part of the body where the legs are linked to the body). The violin shape will have the neck pointing the rear of the spider. Be cautious of this as an the only identifying characteristic. Cellar spiders (daddy long legs) and pirate spiders also have very similar markings to the naked eye.

WHERE TO LOOK FOR THEM:

The Brown Recluse usually chooses to live in woodpiles, sheds, closets, garages, and cellars. The choice habitat for a brown recluse is somewhere dry and undisturbed. When indoors, the brown recluse’s choice home is cardboard, because it is the closest thing to rotting tree bark, which is their natural home.  They can also be found in clothes piled on the floor and left unattended for a few days, behind pictures, and inside shoes not often worn. The brown recluse usually tries to avoid conflict, but if brushed it will usually move very quickly horizontally and will rotate to protect itself. The spider does not jump, but it does lunge when trying to quickly flee.

THE BITE:

Brown recluse spiders are rarely aggressive.  However, the spider usually bites if against skin, like trapped in the shirt or pants. The bite is not usually felt and is most often not painful. The brown recluse has hemotoxic venom (toxins that destroy red blood cells and other living tissue) and this is why the bite can painful and itchy in 2-8 hours. The pain and the bite location can become irritated and the wound can become gangrenous within 12-36 hours and grow as large as 25cm (10 inches)

If bitten, capture the spider in a jar or bag and take with you to the emergency room for a proper identification. Medical attention is mandatory for brown recluse bites. 

Dr. Mike Merchant, Texas A&M AgriLife Extension Entomologist, has a fact sheet on control of brown recluse spiders. Here is information from the National Institute of Health if you think you have been bitten by a brown recluse.

 

Brown recluse spider, female. Photo Credit: Bart Drees, Texas AgriLife Extension Service.