Black Widow SpidersDr. Jim Fredericks
Thursday, October 3, 2013
Everything You Need to Know About This Venomous Species
Black widow spiders
are the creatures of scary stories told on Halloween night – deadly
females that kill and eat the males and who are poisonous to anyone
that dares come near.
While there are elements of truth to these stories, the habits
of black widow spiders aren’t any different than the habits of
other species of spiders. However, of the spiders that interact
with humans, the black widow’s characteristics coupled with its
health risk make it one of the most dangerous spiders that can be
found in or around the home. Being aware of where to find these
spiders and the risks they pose can help protect you and your
family from being bitten.
How dangerous are
Black widow spiders are one of a small number of
structure-invading spiders that have both fangs big enough to
pierce human skin and venom potent enough to cause severe side
effects. According to the Centers for Disease
Control and Prevention (CDC), the black widow is the most
venomous spider in North America. However, bites are very rarely
fatal as the amount of venom injected is so small, and very few
people have interactions with black widows in which they are
In the case of a black widow bite, the Food and Drug
Administration (FDA) does produce an antivenin that can be used to
counteract the effects of the venom, reducing the side effects and
possibility of death in bite victims.
What do they look like?
The good thing about black widows is that they have a very
unique appearance. They can be recognized by most people and are
easily identified by an expert. Their characteristic all black body
is very round and there is a red hourglass or split-hourglass shape
under their abdomen. Females can be 3/4 of an inch long with legs
over one inch long. Males are about half the size of females.
Where are you likely to
Black widows can be found both inside structures and outdoors.
They prefer sheltered and protected areas where potential prey has
the opportunity to be caught in their webs. Widows are most active
during the night when they spend time spinning webs. These webs are
very irregular and can be about one foot in diameter.
Outside, they are usually found under stones, in woodpiles or
around decks. Occasionally they might live on low tree branches or
in shrubs. However, being partial to protected areas makes man-made
structures ideal places for black widows to seek shelter. Common
places in the home for these spiders to live are in cluttered or
seldom-used areas in the garage, basement or a crawl space.
How do you prevent a
black widow spider infestation?
The best techniques for preventing black widow spiders are
keeping the home free of clutter and sealing possible entry
pest-proofing steps such as installing screens and weather
stripping are effective at keeping black widows from getting into
your home. Removing old boxes and other unwanted items from dark
corners will reduce the number of places for the spiders to
When cleaning out these areas of the home, be sure to wear a
long-sleeved shirt and gloves to avoid bites from a black widow or
other spider that may already be hiding there. If a spider web is
visible, use caution before putting hands or feet in that area. It
is also good practice to shake out clothing and check in shoes that
have been stored in a basement or garage before wearing them.
How can I recognize a
black widow spider bite?
A bite from a black widow spider feels like a pinprick. Pain is
usually immediate, but bites are not always felt. If it is not
felt, the only evidence will be a slight swelling with two tiny
According to Dr. Jorge Parada, medical advisor for the National
Pest Management Association, symptoms of a bite include fever,
increased blood pressure, sweating and nausea. The main component
in black widow venom is a neurotoxin, which causes pain at the bite
site and then spreads to other areas of the body such as the chest
and the abdomen. Severe reactions could result in muscle
For most healthy people, symptoms of a black widow bite will
dissipate within a few days. However, young children and the
elderly may be susceptible to severe reactions, Parada warns.
Are all black widows
Most bites from black widow spiders occur when a spider’s hiding
place is discovered or a female is protecting her egg sac. Although
they are dangerous, these spiders use their bite as a defense.
Black widow spiders do not bite humans instinctively.
If you suspect an infestation, contact a licensed pest
control professional immediately. This is the safest way to get
rid of black widow spiders in your home and keep your family