Black Widow Spiders

Spiders are arachnids, not insects. Insects have 6 legs, or 3 sets of two while spiders have eight. Most have eight eyes. They don't have ears, but feel sound vibrations through the hairs on their legs. The body is composed of two parts, the head and the abdomen. As they grow they molt, shedding their old skin and forming a new one.

The Black Widow is a medium sized spider with a body about a half-inch in length. The name is derived from the mistaken belief that the female kills the male after mating. This does happen on occasion, but not routinely. There are five species of Black Widows found in the United States with the Southern Black Widow and the Northern Black Widow being the most common.

The Southern Black Widow has a shiny, black globular abdomen with a distinctive red hourglass on its underside. The Northern Black Widow doesn't have the hourglass but a row of red spots down her upper part of the abdomen and two crosswise bars on the underside. The Northern Black Widow may be brown rather than black and can have red legs.

As the name indicates, the Southern Black Widow is found primarily in the southeastern United States however it can be found from Florida to New York and as far west as Arizona. The Northern Black Widow is found primarily in the northeastern United States and Southern Canada. The Western Black Widow, while not as common, can be found along the western seaboard from Canada to Mexico.

The ranges overlap, and most references to the Black Widow Spider do not distinguish between the species. When asked, most people will describe the Southern Black Widow. This can be problematic. Without the hour-glass marking, people may assume they are dealing with a harmless spider rather than a venomous one.

The Black Widow Spider prefers a quiet, undisturbed habitat. They are common around wood piles, found under eaves, shrubbery, basements, and in other inconspicuous nooks and crannies. They are not aggressive but will bite when startled or threatened.

The Black Widow Spider is a tangle-web spider. They are also known as cobweb spiders or comb-footed spiders. The silk used to build the web is sticky and is produced in the spinnerets attached to the spider's abdomen. They build a tangle space web, which is a three-dimensional web, and use the comb of serrated bristles on their fourth set of legs to arrange it.

The Black Widow Spider preys on a variety of insects such as flies, cockroaches, ants, and beetles. When the prey is entangled in the web, the Black Widow comes out of its hiding place and wraps the prey securely in its web. Once is prey is secure, it stabs the prey injecting the venom. It takes about ten minutes for the venom to do its job. Once the prey ceases movement, digestive enzymes are released into the wound. The prey is carried back to the spider's hiding place before being consumed.

After fertilization, the female Black Widow Spider lays her eggs in a woven cup of silk. The egg sacs can hold from 20 to 400 eggs which incubate for 20 to 30 days depending on the surrounding temperature. The egg sac is woven into the web and guarded by the female but once the eggs hatch, cannibalism becomes an issue. The newly hatched spiders are a brownish orange and will stay near the sac for a day or two, but eventually disperse by 'ballooning.' A single thread is spun, which is caught by the wind. The wind carries them to a new location. Locating a protected spot, they hunker down and start building their own web. The cycle can be repeated four to nine times in one summer.

The average life span of the Black Widow varies with the female outliving the male. Cannibalism is an issue and many don't survive their first molt. Although the name "Black Widow" stemmed from the belief that the female ate the male after mating, only one species, the L. mactans (the Southern Black Widow) has been know to do that.

Although the Black Widow is not an aggressive spider, it will bite when startled or harassed. It's also fiercely protective of its egg sac. Many times the bite will go unnoticed, or feel like a little pin prick. The bite location will swell and there will be two red spots surrounded by redness. The reaction to the bite is systemic and the pain will become intense within a few hours. It will be followed by tremors, nausea, vomiting, leg cramps, abdominal pain, loss of muscle tone and a sharp rise in blood pressure. The toxin has also been known to cause breathing difficulties and even render the victim unconscious. The symptoms can continue for up to 48 hours. Despite the severity of the symptoms, less than 5% of the people bitten by a Black Widow Spider die.

While the bite of a Black Widow Spider may not be fatal, it is extremely unpleasant. While they cannot be eliminated, keeping your home and the area around it relatively free of the Black Widow is possible. Remove all materials where they might like to hide such as debris piled in the corner of a garage. If you come across a web, use a stick to knock it down and crush the egg sacs. When transferring wood from a woodpile to the fireplace, wear gloves and pay attention to what you're doing.