Unlike most spiders that are harmless, the brown recluse (or "fiddle back") spider is one of three venomous spiders commonly found in some parts of the United States. The brown recluse is most commonly found in the Midwestern and southern states. The other two common venomous spiders are:
- Black widow - found throughout North America, but are most common in the southern and western areas
- Hobo spiders - found throughout the Pacific Northwest.
Brown Recluse Identification
What it looks like:
- Body: about 1/4 to 3/4 inches long with a velvety appearance caused by the very fine hairs on its body
- Legs: long and thin with fine, brown hairs. No spines on legs.
- Coloring: golden tan to dark brown with a fiddle-like marking. (See Distinguishing Marks below).
- Distinguishing marks: As its nickname implies, the brown recluse/fiddle back spider has a fiddle- or violin-like marking on its back. In some species, however, this marking is very faint. Additionally, most spiders have eight eyes, but recluse spiders have only six, which are set in pairs - with one pair in front and one on each side.
  The brown recluse is sometimes confused with the sowbug spider, because of their coloring and some similarity of features. Its orange legs are the key differentiating characteristic of the sowbug/woodlouse spider.
Where it is found:
- Most prevalent from the central Midwest to the Gulf of Mexico
- Outdoors in dark, hidden spots such as beneath logs, stones, and lumber piles.
- Indoors in dark, undisturbed places such as attics, basements, crawl spaces, closets, ductwork, etc.
- When conditions are favorable, brown recluse populations can build to high numbers.
What it does:
- As indicated by its names, this brown spider is a recluse, preferring to seclusion in hidden areas, and generally avoiding open areas.
- According to Ohio State University's Ohioline, "The brown recluse spider spins a loose, irregular web of very sticky, off-white to grayish threads. This web serves as the spider's daytime retreat, and it often is constructed in an undisturbed corner."
- It leaves its shelter during night-time hours in search of food, and feeds primarily on dead insects.
The Bite of the Brown Recluse
- The brown recluse is not aggressive, but will bite when contacted. Human bites are generally caused by accidental contact, such as rolling over onto a spider while asleep; reaching into areas, such as a closet or lumber pile, where the spider has harbored; or, sometimes, putting a foot into a shoe into which the spider has hidden. This is because this spider cannot bite humans without a counter pressure, such as these accidental contacts trapping the spider against the skin.
- Symptoms of and reaction to the bite of a brown recluse is dependent on the amount of venom injected and the person's sensitivity to it. Most bites cause only a small red mark and eventually heal without scarring, although a severe reaction can result in a lasting crater or hole at the site of the bite.
- Symptoms may include:
- little initial notice or immediate stinging of the bite
- after 2 to 8 hours, a small blister and swelling generally appears
- the surrounding area then turns red and hard
- the area - of up to 2 3/4 inch in diameter, is sometimes termed the "red, white, and blue sign" as it forms into a bluish-white, irregular sinking patch surrounded by redness.
- Full healing of a wound can take months and result in lasting scars.
The Severity of Brown Recluse Spider Bites
If you are bitten, OSU recommends the application of ice to the area and immediate seeking of medical care . Other physical conditions can be mistaken for brown recluse spider bites, so it is important to have the spider for accurate diagnosis and treatment.
How to Control Brown Recluse Spiders
It can be a difficult and lengthy process to control brown recluse spider populations that have gotten into the home because the spiders will harbor in a widely dispersed out-of-the-way places. Thus, as for most spiders, the most effective controlincludes prevention, exclusion, sanitation, trapping, and chemical treatment if necessary. (See Get Rid of Spiders in the Home)