About Brown Recluses
It is that time of the year when we pull out winter clothes from storage or
the back of the closet. Make sure you shake them out and invert the sleeves
just in case a critter has taken up residence while it was stored. We have
large diverse populations of spiders in the southwest. Most of which are
beneficial in controlling undesirable insects or are just minding their own
business trying to make a living every day. All spiders are predatory
animals and have mouth parts equipped with hollow fangs and venom glands.
The venom of most spiders is mildly toxic to man causing a rash or red spot.
Unless you are sensitive to this venom protein in which case any bite can be
of concern. However there are three spiders in our valley from which a bit
can be quite serious. Black widow produces a neurotoxin and two species of
brown recluse produce venom that is hemolytic (Flesh killing).
Most people are aware of black widow so I will not go into
detail on them. I do not know who it is in town that is telling people that
we do not have brown recluse spiders, but they are wrong. In 1990 I sent 4
specimens to the USDA laboratory in Beltsville Maryland and three were true
brown recluse and one was an Arizona recluse a close relative to the brown,
the venom is the same only differing in volume so it is purely academic.
The USDA laboratory notes that there are 6 species of Loxosceles in the
southwest.
The recluse spider family can be distinguished from all other
spiders by the following characteristics: The body of the adult is about 9
mm long or a little bigger then a ¼ of an inch almost a 1/3. The leg span
can be 25 mm or about the size of a quarter dollar. They are tan to brown
and there is a distinctive violin-shaped darker marking on the thorax with
the base of the violin being the head, and the neck point to rear. Recluse
has three pairs of eyes on the base of the violin; this can be difficult to
see without magnification. Other spiders have four pairs of eyes.
By nature recluse spiders do not like being out in the open
hence the name recluse. They are found under rocks, scraps of wood etc in
the wild. They also occupy dark places in building in dry habitats, may be
brought in to homes in firewood, boxes that have been in storage or other
items. In their normal habitat they spin a coarse, sticky, irregular web of
very white silk, on which they are normal found in the day time. They
forage at night in search of prey and many people are envenomed (bitten) at
night.
All species of Loxosceles are seriously venomous to humans. In
1979 Dr. Cazier forced a recluse to bite him on the arm and noted the
results, I am not that dictated to science. There are three major components
of the venom and volume for volume, this venom is much more toxic then that
of the most poisonous snakes. The recluse is not an aggressive spider and
most bites have often been suffered when the spider is trapped inadvertently
between the skin and something else like the in the sleeve of a jacket. They may hide in folds of clothes, or bedding, and bite when the clothes are
donned or the bed occupied.
Most victims have been bitten when putting on
clothing in the morning, and the wounds are on the legs or arms. Little or
no pain is felt at the time of the bite, but pain and local swelling are
experienced in 2-8 hours. A blister forms at the bite, and this become a
center of swelling and redding in the form of a bull’s eye target. In the
next day or two the skin becomes discolored and darkened and a tough scab
may form by the end of the first week. When the scab separates within 2-5
weeks it leaves an ulcer with necrotic base. This is slow to heal,
requiring month to heal with heavy scarring. In severe cases (most are
mild) there may also be joint pain, vomiting, and a fever as high as 104 F
that occurs within 36 hours of the bite and last up to a week.
The bite of a recluse spider, while not usually life-threatening, may cause severe local
and occasionally systemic symptoms that require the sustained attention of a
physician. A neglected bite can result in disfiguration and possible renal
(kidney) failure. If you believe that you or someone else has been bitten
by a recluse spider, visit a physician as soon as possible for examination
and treatment of the bite. Try to find the spider for identification; do
not smash it up too bad. Recluses do not move a lot so you can often find
them in the same area where the bite occurred.
The best defense is Don’t get bitten!! Prevention includes thorough house
cleaning with special attention to dark corners, closets, and sheds and the
like. Shake those jacket out well and invert the sleeves before putting
them the first time, and check firewood piles before getting wood. There is
no reason for alarm at the presence of the recluse spider in your yard or
house, but it is only prudent to kill those you encounter and to eliminate
habitat near your house. Mechanical means (fly swatter or rolled up news
paper) is much more effective the any insecticide.
Eddy County Extension Service, New Mexico State University is an equal opportunity/affirmative
action employer and educator. All programs are available to everyone
regardless of race, color, religion, sex, age, handicap, or national origin.
New Mexico State University, U.S. Department of Agriculture, and the Eddy
County Government Cooperating.
