OPEN-FILE REPORT 92


 Spiders can pose another hazard and one spider, in particular, is dangerous and common
in Florida. The black widow (Latrodectus mactans) is considered to be the most venomous
spider in North America, with venom that is reportedly 15 times stronger than a rattlesnake's
venom (National Geographic, 2008). Black widow spiders are easily recognized by the presence
of a red "hourglass" marking on the underside of the abdomen. The photos of the black widow
were taken when a piece of Suwannee Limestone was rolled over to look at the underside.
Fortunately, the sample was turned over with a rock hammer and not a bare hand, something that
is a good habit to get into to avoid being bitten. The bite of the black widow spider may feel like
a pin prick, but the initial pain goes away rapidly, leaving localized swelling and two tiny red
marks at the site of the bite. Cramps in the shoulder, thigh and back muscles generally begin
within 15 minutes to a few hours. In severe cases of a black widow bite, pain may spread to the
abdomen, blood pressure may rise, there may be nausea, sweating and difficulty in breathing.
Death can result, depending on the victim's age, physical condition, and the location of bite.
Death seldom occurs, however, if a physician is consulted and treatment is promptly sought.
 Another very common spider encountered while doing field work in Florida is the golden
silk spider (Nephila clavipes). While this spider is not poisonous, its web does pose an
annoyance when hiking through the woods. During the summer and late fall, the large webs of
this species are extremely common and it is not uncommon for hikers to walk through the webs
and have the spider end up on them as in the case of FGS staff member Tom Greenhalgh in the
photo below. The bite from this spider is generally less painful than a bee sting and produces
only localized pain and redness, which quickly dissipates.