Floridian Nature

Learn about Florida's beautiful and unique nature.

Florida Insects: Widow Spiders
black widow spider found in FloridaThe four species of widow spiders are very similar in body shape. All are about 1/2" long with legs extended. Their life cycle is also similar. The female lays about 250 eggs in a pear-shaped egg sac that is about 1/2" to 5/8" in diameter. The eggs hatch in about 20 days. As the young spiders mature, they construct a loosely woven web and capture progressively larger prey. In Florida, all the widows except the northern black widow breed year-round. Anyone bitten by a spider should preserve it in rubbing alcohol for positive identification. Most spider bites are not considered dangerous, but if you suspect one of the widow or brown recluse spiders, get medical attention immediately.

brown widow spider in FloridaBrown Widow Spiders- The brown widow is established pretty much throughout the Florida peninsula. It is found most often south of Daytona Beach along the coast. The brown widow builds its web in secluded, protected sites around our homes, often very near our presence.  It has a fondness for buildings but will construct its web in all kinds of man-made structures, and even vegetation.  Some typical sites include inside old tires, empty containers such as buckets and nursery pots, mail boxes, entry way corners, under eaves, stacked equipment, cluttered storage closets and garages, behind hurricane shutters, recessed hand grips of plastic garbage cans,  underneath outside chairs, and in branches of shrubs.

brown widow spider coloringBecause brown widow spiders vary from light tan to dark brown or almost black, with variable markings of black, white, yellow, orange, or brown on the back of their abdomens, brown widows are not as easy to recognize.  The underside of the abdomen, if you can see it, contains the characteristic hourglass marking. Unlike the black widow, the hourglass is orange to yellow orange in color. The brown widow is also slightly smaller than the black widow.  The egg sac looks like an old naval mine or a sandspur seed.

brown widow spider egg sacBrown widow spiders are extremely timid; the only bites reported have resulted from a spider being accidentally trapped against the victim's body. Brown widow spider bites are however becoming more common. The venom of the brown widow may be twice as potent as the black widow, experts believe, but the brown widow is less inclined to inject larger amounts of venom. Brown widow bite symptoms can include pain, rigidity in the muscles of the abdomen and legs, swelling, nausea, vomiting and in severe cases a sharp rise in blood pressure. Generally, the symptoms of the brown widow tend to stay localized to the bite site, whereas the black widow's symptoms are more widespread.

southern black widow spider in FloridaBlack Widows - The southern black widow is the most widespread widow spider in Florida. It is glossy black and has a complete hourglass marking on the underside of the abdomen. The black widow spider's body is about 1/4-1/2 inch long and 3/4 to 1 and inches wide when legs are spread out. The northern black widow has the same general appearance, but has two red triangles resembling an hourglass and a row of red spots on top of the abdomen. The northern species is found west of Tallahassee, primarily in forests, with its webs three to 20 feet above the ground. The southern black widow is usually found outdoors in protected places, such as under rocks and boards, and in and around old buildings.

The black widow spider’s venom is a potent neurotoxin and is considered the most venomous spider in North America. However, the female injects such a small dose of venom that it rarely causes death. They are timid and solitary, and often bite only when disturbed. All encounters with humans can be attributed to the female. The bite of the black widow and other widow spiders usually feels like a pin prick. The initial pain disappears rapidly, leaving local swelling and two tiny red marks. Muscular cramps in the shoulder, thigh and back usually begin within 15 minutes to three hours. In severe cases, pain spreads to the abdomen, the blood pressure rises, and there is nausea, sweating and difficulty in breathing. Death may result, depending on the victim's physical condition, age and location of bite. Death seldom occurs if a physician is consulted and treatment is prompt.

red widow spider found in central FloridaRed Widow Spiders- The red widow has a black abdomen with a single flattened red triangle on the underside. On the back are rows of red spots, each of which are surrounded by a yellow circle. The head region and legs are red-orange in color. The red widow spider's web begins as a typical tangle web in the interior of a small palm or palmetto, but then continues as a sheet of silk onto one of the lateral open leaves. Red widow spiders are endemic to Florida. It occurs in sandpine scrub from Marion County to Martin County. Because of both its rarity and its beautiful coloring, the red widow spider is a collector's item for people who collect spider specimens. Little is known of the bite of the red widow, but its venom is probably quite toxic to mammals.  
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