The
black widow is one of the two dangerous
spiders found in the United States. In
fact, it is considered the most venomous
spider in all of North America. Despite
all of this, the mortality rate is
actually quite low--less than one
percent. So, if you are a healthy person
between the ages of 15 and 60, your
chances of surviving a black widow bite
are very high.
The characteristic markings of female
black widows (the poisonous ones) are
red or yellow hourglass shapes on the
abdomens. Their abdomens are jet black,
rounded, and globular in shape. Female
spiders measure about ½”, and, with
their legs spread, 1 ½”. Adult males are
half this size, harmless, and have their
own unique markings. Besides having
longer legs and smaller bodies than the
females, the males have yellow and red
spots and bands over their back. The
immature stages of both sexes also
feature their own distinctive markings.
When a black widow is newly-hatched,
they are white or yellowish white in
color and gradually acquire black and
varying amounts of red and white with
each molt (skin shedding). Young
spiders, like the males, are harmless.
Black widow spiders spin webs made of
coarse silk. They usually do this in
dark places outside near the ground.
Occasionally, they are constructed
indoors, but usually are spun in trash,
rubble piles, and under or around houses
and outbuildings. During the course of a
summer, 4 to 9 ½” egg sacs are produced.
These sacs yield approximately 300 to
400 eggs. However, only 1 in 12 young
survive the 2 to 4 week incubation
period due to cannibalism.
If the young spiders are able to survive
without falling victim to cannibalism,
it takes them 2 to 4 months to complete
their growth. Females molt 6 to 8 times
while males molt 3 to 6 times. All in
all, females mature approximately 92
days after egg sac emergence. After
maturation, they live approximately 180
days. Males mature 71 days after sac
emergence and then have only 30 days of
adult life.
After mating, a female spider will eat
the male. The only hope the male has of
cheating death is if the female is
well-fed (read: ate enough babies). If
the male survives another day, he will
attempt to mate with another female
until his luck runs out and he becomes
female food.
Females hang belly upward, rarely
leaving the web. Cold weather and
drought may drive these spiders into
buildings from their outdoor habitat.
Female are shy and nocturnal, rarely
leaving their hidden webs voluntarily.
Typical prey in usually includes
cockroaches, beetles, and other insects.
So, if you have black widows, you can
take comfort in the fact that your
insect population is lower than it would
be without having black widows.
Outbreaks of black widows occur
sporadically. An area may have thousands
one year and none the next. In sand
dunes areas black widows may be present
every year. Seasonal weather and
alternating cold and hot temperatures
are detrimental to survival.
Although the venom of the black widow
spider is 15 times as toxic as the
prairie rattlesnake, the amount injected
during a bite is drastically smaller,
thereby making it much less toxic. The
mortality for a black widow bite is less
than one percent as opposed to the
prairie snake's, which is 15 to 25
percent.
There are several contributing factors
that determine the severity of a
person’s bite. These include the area of
the body bitten, amount of venom
injected, depth of the bite, seasonal
changes, and temperature. The actual
bite feels like nothing more than a
pinprick, if it is felt at all.
Sometimes, people don’t even know
they've been bitten.
After a bite, the first symptom may only
be a slight local swelling and two faint
red spots surrounded by local redness.
After one to three hours, intense,
agonizing pain begins and may continue
for up to 48 hours. Pain usually
progresses from the bitten area up or
down the arm or leg, finally localizing
in the abdomen or back. At this time,
the abdominal muscles may become rigid
and board-like with severe cramps.
Muscles and the soles of feet may become
painful and eyelids may become swollen.
Other symptoms may include nausea,
excessive and profuse perspiration,
tremors, labored breathing and speech,
and vomiting. The pulse may become
feeble and the skin clammy.
Unconsciousness and convulsions are
possibilities as is the the potential
for death if medical attention is not
sought immediately. After these symptoms
have passed, complications due to
infection of the bite-area may occur. In
some individuals who do not seek medical
attention, symptoms may diminish within
several hours or days of agonizing pain.
All in all, bites are uncommon and
serious injury and death are even less
common.
If bitten, try and collect the spider
that bit you and remain calm. Get
medical attention immediately by
contacting your physician, hospital, or
Poison Information Center. First aid is
of limited help although a mild
antiseptic such as iodine or hydrogen
peroxide may help to prevent infection.
To prevent black widow spiders from
being an unnecessary hazard, remove
trash, old boxes, piles of lumber, old
rubble piles and other unwanted items
from under or around houses and
outbuildings. It is not a good idea to
walk barefoot or handle firewood and
lumber without gloves. To prevent entry
into the house, install screens on doors
and seal or caulk cracks or crevices
that may look inviting to spiders. Wash
the outside of your house or building,
paying particular attention to areas
surrounding the window wells and other
undisturbed places where webs are often
built. A stiff broom is helpful because
spiders are fragile and consequently,
easily killed.
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