Black widows are poisonous arachnids—animals that have a skeleton outside their body, a segmented body, and eight jointed legs. They are not insects. Their deadly poison is said to be 15 times stronger than rattlesnake venom.
Black widows use a silk-like substance to weave tangled-looking webs, typically close to the ground in covered or dark places, such as near drain pipes or under logs. The female hangs upside down in the web to await her prey, exposing her bright markings as a warning to potential predators.
The black widow senses vibrations to the web. When an unlucky intruder gets trapped, the spider immediately begins weaving its glue-like webbing around it. Insects such as flies, mosquitoes, or even larger prey like grasshoppers are typically caught. Once captured, the black widow injects its victims with poison, paralyzing them.
The tips of the black widow’s legs are coated with an oily substance that prevents the black widow from getting caught in its own web.
Adult male and female black widows live solitary lives, meeting only to breed. The female black widow lays approximately 200 eggs. The eggs incubate for some 20 days in a small, round papery sac that’s attached to the mother’s web. After hatching, the baby spiders stay in the cocoon for up to one month.
Three species of poisonous North American spiders carry the common name black widow under the genus Latrodectus.
Each species occupies a distinct region of North America, as their names suggest: Eastern black widows (L. mactans), northern black widows (L. variolus), and western black widows (L. hesperus). These three species have very similar physical and behavioral characteristics.
The name “black widow” comes from the female’s habit of eating the male after mating. The female black widow is approximately 1.5 inches (38 millimeters) long. The male is about half the female’s size. The black widow is prey for birds and other spiders.
Although poisonous, the black widow is not considered aggressive unless threatened. In fact, the male black widow is reclusive and hardly ever seen by humans. While the black widow’s poison is rarely fatal to humans, it can cause severe pain and nausea.