Summer 2003

Spiders. Just mention the name and some people get the creeps. All spiders are poisonous to some degree in that they all have poison glands that produce toxins used to subdue or kill their prey. Most spiders are not only harmless, but they play an important role in the balance of nature.

Fortunately, of the thousands of species of spiders known worldwide, only a few are dangerous to humans. Only two of the hundreds of species that have been found living in Mississippi are considered dangerous. All other either lack the biting power or the venom to cause much harm. In the Spring, 2003, issue of Wildlife Mississippi Magazine, I featured the brown recluse. Now, let's take a look at the dangerous black widow.

The black widow (Latrodectus mactans) comes from the folklore that the female devours the male after mating. This rarely, if ever, occurs. Found through out the southern United States, the black widow is also known as the "hour-glass spider" and the "shoe-button spider." The adult female is glossy black with an abdomen bearing a characteristic crimson hour-glass marking on the underside. The crimson marking may vary from the distinct hour-glass shape to a design of two or more triangles or blotches, or sometimes only an irregular longitudinal stripe. Immature females may have an irregular red stripe or pattern on top of the abdomen as well as the red marking below. The female may exceed one and one-half inches in overall length.

Males are somewhat smaller, rarely exceeding one and one-fourth inches in length, with a red stripe or pattern on top of the abdomen. Because of its much smaller fangs and poison sac, the male is not dangerous to humans.

A female black widow is found with her web and egg sac in protected places, such as firewood piles, brush heaps, stumps, stone or brick piles, barns, abandoned houses, garages, outdoor privies, long grass and gardens. The spider spends her life on an established web feeding on insects and guarding her eggs. The normal life cycle, and probably the normal life span, is one year. However under ideal conditions they may live nearly two years.

The incidence of black widow bites to humans is rare, although the spiders are very common. Widows are ordinary shy and retiring, but they will defend their eggs and bite when cornered. Most bites occur in outdoor privies, a favorite nesting place. The incidence of widow bites have been reduced dramatically since the widespread introduction of indoor plumbing.

When the black widow does bite, it causes no more discomfort than a pinprick. In fact, some victims are not even aware that they've been bitten. A slight local swelling and two tiny red spots may occur at the sight of attack. Within a few hours, however, intense pain and stiffness begin. Other symptoms may include chills, fever, sweating, nausea and severe abdominal pain. Although in most cases, the symptoms will disappear without treatment in two to three days, medical aid should be sought immediately. Black widow bites have caused death from heart and lung failure, but the mortality is estimated at only four to five percent.

Many people have a strong fear of spiders. It is important to remember that although the black widow is dangerous, it is not aggressive. A large number of bites attributed to spiders are actually insects such as mosquitos, assassin bugs and beetles. Most spiders are harmless, and all of them play an important role in nature.

This article was written by Paul Hartfield, an endangered species biologist with the U.S. Fish and Wildlife Service in Jackson, Mississippi.