Widow spiders come from the genus Latrodectus. Although there are thirty-one species of widow spiders throughout the world, the most well known are the black widow spider of North America and the red back spider of Australia. Widow spiders are known for possessing potent neurotoxic venom. Fortunately only a small amount is injected per bite.
North American Species
There are three varieties of black widows found in North America. The southern black widow (L.mactans) inhabits the southeastern portion of the US, ranging from Florida north to New York, and west to Texas and Oklahoma. The northern black widow (L.variiolus) inhabits the northeastern part of the United States, as well as the southeastern part of Canada. The third variety, known as the western black widow (L.Hesperus) occupies the western parts of the US, as well as, the majority of Mexico and the southwestern part of Canada. It is common for the different species to overlap territories. All three species have much in common, and are referred by many as being the most poisonous spider to inhabit North America. Their venom has been reported by scientists to be fifteen times more potent than rattlesnake venom.
Identification
Black widow spiders can be identified by two connected triangles on their underbelly, appearing as an hourglass. The hourglass marking is typically red in color, but can also appear yellow or orange. The abdomen of the female is spherical and usually black and is approximately a half-inch long. The spider with spread legs is around one and a half inches in length. Males are about half the size of the female and have smaller bodies and longer legs. The male widow has red spots along the upper midline and white lines appearing on its sides. The female widow fangs are small and can just penetrate skin to the point of enabling venom to be transferred. The male black widow’s fangs are smaller and tend to be less venomous and generally not as dangerous to humans.
Habitat
Black widows prefer undisturbed areas. These include sheds, hollow logs, tree stumps, piles of debris and garages. Once they make a web, they rarely will move from the spot. The web is very strong consisting of crisscrossed patterns. During the day the spider retreats to an isolated spot on the web that’s covered with dense silk. At night the spider hangs belly up in the center of the web, waiting for prey. Black widows eat many varieties of insects including roaches, beetles and other spiders. Their predators are mainly different types of wasps. Black widows also place and guard their egg sacks on the web. Each sac may contain several hundred eggs, that hatch in usually less than a month. The spiderlings usually take two to four months to mature. The sole purpose of the male is to mate with the female, and contrary to what is thought, the majority isn’t eaten by the female. Females can live up to five years, while males live shorter lifespans.
Control and first aid
The best way to avoid black widows is to control them, if present in the area. This includes night inspection to locate these arachnids, since they’re nocturnal. Management includes wearing long sleeve shirts when working outdoors, clothing inspection with the shaking out of clothing or shoes before getting dressed. Other measures include the installation of screens around the house, avoiding household clutter, frequent vacuuming and the use of insecticides. If one is accidentally bitten, the application of ice packs, the collection of the spider for identification purposes and seeking immediate medical attention is advised. According to professor Susan Jones of Ohio State, only one percent of humans die from widow bites. Those at risk include the medically compromised, those with heart conditions, the very young and the very old. Antivenom is available, so many do recover, if prompt medical attention is sought.
Widow spiders deserve our respect. We can easily identify them and safely remove them from inhabited areas, mainly by avoiding clutter along with the prudent use of insecticides. If bitten, prompt medical attention will prevent most negative sequalae.
References
Farrand, J. 1988. Familiar Insects and Spiders. New York: Chanticleer Press.
Gertsch, W. 1979. American Spiders. New York: Van Nostrand Reinhold.
