Black widow spiders (Latrodectus mactans) are found throughout the Western Hemisphere. A female black
widow is much more likely to deliver more venom than a male spider.
Female black widows are long-legged, shiny, coal-black spiders with an
orange, red, or yellow hourglass shape on the underside. The female black widow
is usually about
1.5 in. (3.8 cm) long, but may
Black widow spiders tend to
bite defensively when their webs are disturbed. Black widow spiders are
frequently found in low-lying webs in garages, barbecue grills, around swimming
pools, and in wood piles. Bites to babies and children may be more serious than
bites to adults. Signs and symptoms of a black widow bite include:
Minimal pain at first, followed by sharp pain and swelling and
redness at the site of the bite.
One or two small fang marks like
tiny red spots.
In some cases, severe symptoms appear within 30 to 60
minutes. These include:
Muscle cramps and spasms that start near the
bite and then spread and increase in severity for 6 to 12
Chills, fever, nausea, or
Severe abdominal, chest, or back
Stupor, restlessness, or shock.
Severe high blood
A doctor should be contacted immediately when a person is
bitten by a black widow spider.
William H. Blahd, Jr., MD, FACEP - Emergency Medicine & H. Michael O'Connor, MD - Emergency Medicine
How this information was developed to help you make better health decisions.