Florida Department of Agriculture and Consumer Services
In Florida, only two main types of venomous spiders occur: widow spiders and recluse spiders.
Three species of widow spiders are native to Florida, and a fourth species has been introduced. No species of recluse spiders are native to Florida, but three species have been intercepted and occasionally have established populations in single buildings at scattered locations.
Both types of spiders tend to be found in similar places, which is in or under objects where their presence is not necessarily obvious. In the interest of safety, it is recommended that people engaged in activities in which they cannot see where their hands are being placed (such as lifting boards or firewood, or reaching into storage boxes) should wear gloves to prevent being bitten by a hidden spider. Also, clothing — especially if unused for a considerable time — should be checked before wearing, as a spider may have taken up residence within it.
The widow spiders, genus Latrodectus (family Theridiidae), are worldwide in distribution. Females range from 8-15 mm in body length; males are smaller, sometimes very small (2 mm). Most have globose, shiny abdomens that are predominantly black with red markings (although some may be pale and/or have lateral stripes), with moderately long, slender legs.
These spiders are nocturnal and build a three-dimensional tangled web, often with a conical tent of dense silk in a corner where the spider hides during the day. In nature, most species are found under rocks and logs, but they readily adapt to human-altered environments, where they are most commonly found in outbuildings (sheds, barns, privies), water meter holes, nursery cans, and under any item or structure (e.g., barbeque grill, slide, sand box) that has been undisturbed for a lengthy period.
Formerly, most bites by black widows (almost all by female spiders) occurred in outhouses, but presently Latrodectus bites occur most frequently when the spider is trapped against human skin, either when someone reaches under an object where the spider is hiding or when someone puts on clothing, gloves or shoes containing the spider. Widow spiders are generally very timid and only bite in self-defense when they accidentally contact humans.
Bite symptoms are systemic, spreading through the lymphatic system, and usually start about one to three hours after the bite. The most common symptoms are intense pain, rigid abdominal muscles, muscle cramping, malaise, local sweating, nausea, vomiting and hypertension. If left untreated, Latrodectus bite symptoms usually last three to five days. Calcium gluconate and/or antivenin may be administered to relieve or counteract symptoms.
There Are Four Species of Widow Spiders in Florida:
- Latrodectus mactans, the southern black widow
- Latrodectus variolus, the northern black widow
- Latrodectus bishopi, the red widow
- Latrodectus geometricus, the brown widow
The brown recluse has been found in Alachua, Bay, Duval, Jefferson and Leon counties. It typically has a dark violin-shaped mark, although the color is variable.
The Mediterranean recluse has been found in Dade, Escambia, Orange and Osceola counties. It is very similar in appearance to the brown recluse, but the violin mark tends to be lighter in color and has parallel sides.
The Chilean recluse has only recently been found in Florida, in Polk County. It is the largest and most dangerous of the recluse species. The violin mark of this species is dark and wider in front than behind. View a Pest Alert on the Chilean recluse [ ].
More information about recluse spiders in Florida can be found in this citation: Entomology Circular 406 [ ].
There are many websites devoted to spiders. A few are listed below.