Brown Recluse Spider

The brown recluse spider is a concern many people share in Missouri. If you don’t personally have a brown recluse story, you probably know someone who does. Unfortunately, other harmless spiders are often mistaken for the poisonous brown recluse. Brown recluse are extremely secretive and are often hard to spot. They like to hide in places where they are unlikely to be found. Here are some helpful tips to aid in identifying and controlling this worrisome creature.

Identification
The mature brown recluse spider, as well as some other species of recluse spiders, has a dark violin marking with the neck of the violin pointing toward the bulbous abdomen. The abdomen is uniformly colored, although the coloration can range from light tan to dark brown, and is covered with numerous fine hairs that provide a velvety appearance. The long, thin, brown legs also are covered with fine hairs, but not spines. Adult brown recluse spiders have a leg span about the size of a quarter. Their body is about 3/8 inches long and about 3/16 inches wide. Males are slightly smaller in body length than females, but have proportionally longer legs. Both sexes are venomous. The immature stages closely resemble the adults except for size and a slightly lighter color. Whereas most spiders have eight eyes, recluse spiders have six eyes that are arranged in pairs in a semicircle on the forepart of the cephalothorax. A 10X hand lens or microscope is needed to see this diagnostic feature. In order to determine the exact species of Loxosceles, the spider’s genitalia need to be examined under a high-power microscope. This requires the skills of a spider expert.

Controlling brown recluse
Glue boards (or sticky boards) are a good way to survey for and control brown recluse infestations in your home. Glue boards can be purchased at most grocery or hardware stores. The best glue boards for capturing brown recluse are thin without a raised edge. Brown Recluse spiders prefer warm, dry locations. Here are some places where they are typically found indoors:

• Inside shoes
• Inside dressers
• In showers and bathtubs
• Underneath couches, tables and chairs
• In bed sheets of infrequently used beds
• In stacks of clothes
• Behind baseboards.
• In boxes
• Behind pictures

• Shake out clothing and shoes before getting dressed.
• Inspect bedding and towels before use.
• Wear gloves when handling firewood, lumber, and rocks.
• Inspect gloves for spiders before putting them on.
• Remove bedskirts and storage boxes from underneath beds.
• Move the bed away from the wall.
• Exercise care when handling cardboard boxes.

First Aid
If bitten, remain calm, and immediately seek medical attention. Apply an ice pack directly to the bite area to relieve swelling and pain. Collect the spider (even a mangled specimen has diagnostic value), if possible, for positive identification by a spider expert. A plastic bag, small jar, or pill vial is useful and no preservative is necessary, but rubbing alcohol helps to preserve the spider.

An effective commercial antivenin is not available. Some physicians administer high doses of cortisonetype hormones to combat hemolysis and other systemic complications. Treatment with oral dapsone (an antibiotic used mainly for leprosy) has been suggested to reduce the degree of tissue damage. However, an effective therapy has not yet been found in controlled studies.

Richard Houseman
573-882-7181
and
Tammy McNiel