Coachella Valley Mosquito and
  Vector Control District

Brown Recluse Spiders (a.k.a. Violin Spiders or Fiddleback Spiders) Loxosceles sp.

These spiders are sandy or orange-yellow in color with a light brownish-gray abdomen.  The body is approximately 3/8" in length with long thin legs.  It has six eyes which, are arranged in a very distinctive semi-circular pattern.  There is a faint violin-shaped mark on the midsection.

Distribution

The brown recluse spider is most commonly found from Minnesota to Maine south to Florida and west to Arizona and Wyoming. Although the brown recluse does not live in California, we do have four species of native recluse spiders. The most common is the desert recluse L. deserta. In addition L. laeta, that causes sever necrotic lesion sometimes referred to as “gangrenous spot”, has been introduced and is well established in Los Angeles County, California.

Behavior

Brown Recluse spiders are NOT aggressive, and normally attempt to escape whenever they feel threatened.  Bites generally occur when the spider is inadvertently trapped, however, due to their reclusive nature contact with humans is minimal.  Brown Recluse spiders are sometimes found in buildings or homes that are generally dry, littered, and undisturbed for long periods of time.  The web of the Recluse is loose, thin, and unorganized.  Typically the web is made on the ground surrounding the spiders hiding place.

The Bite and First Aid

The bite of a Brown Recluse may cause an immediate or delayed (2-3 hours) pain reaction depending on the sensitivity of the victim or the amount of venom injected.  At the center of the bite a cone-shaped sore may develop.  This sore will rapidly transform into a white crater, which is surrounded by red, swollen tissue that slowly increases in area over time.  The white colored tissue will eventually turn black as the tissue dies.  This process is referred to as necrotic arachnidism.  The black tissue may fall off yielding a larger crater.  The process of dead tissue falling off, each time revealing a larger crater can continue repeatedly.  The venom of the Brown Recluse is extremely toxic and will continue to destroy tissue for long periods of time.  The sore may take months to heal, or in some extreme instances, amputation and/or death cam result.

If you suspect that you have been bitten by a Brown Recluse spider seek IMMEDIATE MEDICAL ATTENTION.

Preventive Measures

Check seldom-worn clothing or shoes before wearing them.  Inspect your bed and bedding before going to sleep at night.  Wear gloves and tap or thump on storage boxes, lumber, etc. before moving them.  Shake out towels and sheets from linen closet before using them.

Prevention and  Control

Insect proof houses with window and door screens.  Use yellow colored light bulbs outdoors to prevent attraction of insects.  Trim shrubbery away from windows.  Eliminate or reduce harborage areas around the home and yard.  Spray residual pesticides, if needed, taking care to follow the labels instructions completely.  Destroy spiders and webs with a stick, broom, vacuum, or other device that allows you to stand away from the spider and/or web during destruction.

Precautions