Black Widow Spider
Females are 1-2" in diameter
Males much smaller
The female black widow is shiny black with a red hourglass
on abdomen; however this does not always have to be the case.
The red hourglass could take the form of a red dot or many
variations of shapes.
The black widow is common in fields, woodpiles, and unoccupied
dwellings. Black widows are found in every state except Alaska.
Black widow venom is primarily
a neurotoxin, which as a rule does not cause local tissue
death and destruction. Best known for widespread muscle spasm
and often mimics that of a severe abdominal problem i.e. acute
appendicitis, or ruptured ovarian cyst.
The initial bite is very painful, but can go unnoticed. The
surface of the skin may display two red bite wounds, one,
or none. The worst pain is in the first 8-12 hours, symptoms
may continue for several days.
All children, pregnant women and individuals with hypertension
should be admitted to a hospital.
Antivenom is available.
Outdoor treatment for Black Widow bites:
- Clean and irrigate the wound.
- Application of ice or cool compresses.
- Pain medication, muscle relaxants if available.
- Transport immediately.
Mature Black Widow Above
Photos by Wayne Talley, North of Dallas, TX
Immature Black Widow Below
Captured by Launa McCray, R.N.
Photos by Dan Williams Psy. D., PA-C
Black widow bite symptoms
Initially, almost all bites from the latrodectus species is
felt as an immediate pinprick sensation, and local pain. In
approximately one hour after the bite, a small, erythematous
area develops. This becomes larger with a blanched center.
The venom acts through a calcium-mediated mechanism, which
is the release of acetylcholine and nor-epinephrine. Subsequently
, the vast majority of patients, around 70%, do experience
hypertension, nausea, light sensitivity to the eyes, which
is called photophobia, difficulty breathing, diarrhea, and
muscle spasms and aches. These individuals can present like
an acute abdomen, and mimic a ruptured ovarian cyst or appendicitis.
In one study in Australia, however, around 70% of the individuals
only presented with local symptoms and did not present with
Intravenous narcotics for pain, and the benzodiazepines help
tremendously. In the past, calcium gluconate infusion was
thought to be helpful. However, it is not recommended any
longer. Anti-venom against the latrodectus species is available
by Merck and Company. Advise only to use in severe cases.
You need to weigh using the anti-venom vs. the presentation
of the patient. It is also important to dilute the anti-venom.
Please see Merck and Company handout with the latrodectus
anti-venom for dilution.