BROWN RECLUSE SPIDER
The brown recluse belongs to a group
of spiders that is officially known as the "recluse spiders" in the genus Loxosceles (pronounced lox-sos-a-leez). These spiders are also commonly referred to as "fiddleback" spiders
or "violin" spiders because of the violin-shaped marking on the top surface of the cephalothorax (fused head and
thorax). However, this feature can be very faint depending on the species of recluse spider, particularly those in the southwestern
U.S., or how recently the spider has molted.
Identification
 |
| not actual size |
| Recluse spiders have six eyes that are arranged in pairs. |
In
the mature brown recluse spider as well as some other species of recluse spiders, the dark violin marking is well defined,
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 males 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 (see close-up view). 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.
Control
Control of indoor infestations
of the brown recluse spider can take a long time (6 months or more) and can be difficult because humans have a very low tolerance
for this pest, it tends to be widely dispersed within infested buildings, and it seeks secluded sites. Control of spiders,
including the brown recluse, is best achieved by following an integrated pest management (IPM) approach. IPM involves using
multiple approaches such as preventive measures, using the Cahaba Spider Trap that works 24 hour a day and
chemical treatment when necessary.
Preventing spider bites
- Shake out clothing and shoes before getting dressed.
- Inspect bedding
and towels before use.
- Wear gloves when handling firewood, lumber, and rocks (be sure
to inspect the 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 (recluse spiders often are found in the space under folded cardboard flaps).
- Place
The Cahaba Small Spider Trap along walls, under beds, in closets and any place you may need.
Exclusion
Install tight-fitting screens on windows and doors; also install door sweeps. Seal or caulk cracks and crevices where spiders can enter the house. Install
yellow or sodium vapor light bulbs outdoors since these attract fewer insects for spiders to feed upon. Tape the edges of cardboard boxes to prevent spider entry. Use plastic
bags (sealed) to store loose items in the garage, basement, and attic Use the Cahaba Small Spider Trap
out side and near entry doors. Sanitation
- Remove trash, old boxes, old clothing, wood piles, rock piles, and other unwanted items.
- Eliminate clutter in closets, basements, attics, garages, and outbuildings.
- Do
not stack wood against the house.
- Clean up dead insects that the brown recluse spider
can feed on.
Non-chemical control
- Use
the Cahaba Small SpiderTrap
under beds, in closets and any place needed to capture spiders.
- Dust and vacuum thoroughly to remove spiders, webs, and egg sacs (dispose
of the vacuum bag in a container outdoors).
- Use a rolled up newspaper or fly swatter
to kill individual spiders.
Bite Symptoms
The
physical reaction to a brown recluse spider bite depends on the amount of venom injected and an individual's sensitivity to
it. Some people are unaffected by a bite, whereas others experience immediate or delayed effects as the venom kills the tissues
(necrosis) at the site of the bite. Many brown recluse bites cause just a little red mark that heals without event. The vast
majority of brown recluse bites heal without severe scarring. Initially, the bite may feel like a pinprick
or go unnoticed. Some may not be aware of the bite for 2 to 8 hours. Others feel a stinging sensation followed by intense
pain. Infrequently, some victims experience general systemic reactions that may include restlessness, generalized itching,
fever, chills, nausea, vomiting, or shock. A small white blister usually initially rises at the bite site surrounded by a
swollen area. The affected area enlarges and becomes red, and the tissue is hard to the touch for some time. The lesion from
a brown recluse spider bite is a dry, blue-gray or blue-white, irregular sinking patch with ragged edges and surrounding redness--termed
the "red, white, and blue sign." The lesion usually is 1½ inches by 2¾ inches or smaller.
The bite of the brown recluse spider can result in a painful, deep wound that takes a long time to
heal. Fatalities are extremely rare, but bites are most dangerous to young children, the elderly, and those in poor physical
condition. When there is a severe reaction to the bite, the site can erupt into a "volcano lesion" (a hole in the
flesh due to damaged, gangrenous tissue). The open wound may range from the size of an adult's thumbnail to the span of a
hand. The dead tissue gradually sloughs away, exposing underlying tissues. The sunken, ulcerating sore may heal slowly up
to 6 to 8 weeks. Full recovery may take several months and scarring may remain.
It is
difficult for a physician to accurately diagnose a "brown recluse bite" based simply on wound characteristics. It
is absolutely necessary to have the spider for a positive identification. Necrotic wounds can result from a variety of agents
such as bacteria (Staphylococcus, "flesh-eating" Streptococcus, etc.), viruses, fungi, and arthropods (non-recluse
spiders, centipedes, mites, ticks, wasps, bedbugs, kissing bugs, biting flies, etc.). Necrotic conditions also can be caused
by vascular and lymphatic disorders, drug reactions, underlying diseases states, and a variety of other agents.
First Aid
If bitten, remain calm, and immediately seek medical
attention (contact your physician, hospital and/or poison control center). 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. The
surgical removal of tissue was once standard procedure, but now this is thought to slow down wound healing. Some physicians
administer high doses of cortisone-type 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.
