Four species of widow spiders occur in Florida: the southern black widow, the northern black widow, the red widow and the brown widow. All these species are rather large spiders about 1 1/2 inches long with the legs extended.
The southern black widow and the northern black widow are a shiny, jet-black color. The southern black widow has a red hourglass marking on the underside of the abdomen and another red spot at the tip end of the abdomen. The northern black widow has a row of red spots located in the middle of its back and two reddish triangles resembling an hourglass on the underside of the abdomen. The red widow spider has a reddish orange head-thorax and legs with a black abdomen. The abdomen may have a dorsal row of red spots with a yellow border. The red widow lacks a complete hourglass under the abdomen but may have one or two red spots. The brown widow spider varies in color from gray to light brown or black. The abdomen has variable markings of black, white, red, and yellow. On the underside of the abdomen it has an orange or yellowish-red hourglass marking.
The life cycle of the widow spiders are all similar. The female lays approximately 250 eggs in an egg sac which is about 1/2 to 5/8 inch in diameter. The eggs hatch in 20 days and remain in the egg sac from about 4 days to 1 month. The young spiders then molt to the second stage and begin feeding. As the young spiders grow, they construct a loosely woven web and capture progressively larger prey. Male spiders molt 3 to 6 times before maturing. The females molt 6 to 8 times and occasionally eat the males after mating. In Florida all the widows except the northern black widow breed year-round.
The southern black widow is the most widespread widow spider in Florida. It is usually found outdoors in protected places such as in hollows of stumps, discarded building materials, rodent burrows, storm sewers, and under park benches and tables. Around houses, the southern black widow is found in garages, storage sheds, crawl spaces under buildings, furniture, ventilators, and rainspouts. The northern black widow is found west of Tallahassee. It is mainly found in forests with irregular, loosely woven webs 3-20 feet above the ground. The red widow spider makes its web off the ground in palmettos habitats and has only been found in sand-pine scrub associations. The web retreat is characterized by the rolled palmetto frond, and the web is spread over the fronds. The brown widow is established pretty much throughout the Florida peninsula. It is most common on, but not restricted to, buildings. They are also found on bridges and fences as well. The egg sac looks like an old naval mine or a sandspur seed. The spiders are extremely timid; the only bites reported have resulted from a spider being accidentally trapped against the victim's body. They reproduce rapidly, and one female can produce up to 18 egg sacs. Once encountered, a spider is indicative of a widespread population which is extremely difficult, if not impossible given available control methods, to eradicate.
Like most spiders, the widow spiders are shy and will not bite unless aggravated. All four species have a strong venom. The southern black widow is involved in most poisonous spider-bite cases in Florida. The bite of the black widow is not always felt, but usually feels like a pin prick. The initial pain disappears rapidly leaving a local swelling where two tiny red spots appear. Muscular cramps in the shoulder, thigh, and back usually begin within 15 minutes to 3 hours. In severe cases, pain spreads to the abdomen, the blood pressure rises, there is nausea and profuse sweating, and difficulty in breathing occurs. Death may result from the venom, depending on the victim's physical condition, age, and location of the bite. However, death seldom occurs if a physician is consulted, and treatment is prompt.
If you suspect that a widow spider has bitten you, capture the specimen for identification and immediately consult a physician. For additional information, your doctor may wish to contact your local poison control center.