Latrodectus hesperus

Westerm black widow spiders, Latrodectus hesperus, live in the warmer regions of the United States. This species can be found in all four of the deserts of the American southwest. (Desert USA, 1996; Encyclopedia Britanica, 1999-2000; Vest and Eagle Rock Research, 1999)

Black widow spiders live under ledges, rocks, plants, and different types of debris. Webs are usually built near to the ground. Webs are sometimes built inside trash cans, piles of trash, as well as under or around houses. When the weather changes from warm to cold, black widows are most likely to find places inside of homes in which to live or spin their webs. in order to prevent black widows from invaiding a home, home owners should remove materials where these animals can hide. If a person happens to find an egg sac, it should be removed with an object other than one's hand. (Desert USA, 1996; Jones, 1991)

Adult female black widow spiders are usually black and shiny. Black widows are most commonly recognized because of the reddish hourglass shape on the underside of the abdomen. Females measure an average of 3.5 cm in length, and typically have a very round abdomen.

Adult males are half the size of females. Their bodies are smaller, but they have longer legs than the females. Males have yellow and red bands and spots dorsally.

Newly hatched black widows are white, but can sometimes be a yellowish-white. As they get older, they slowly turn black. Mature black widows can vary in the amounts of red and white on their bodies. (Bisacre et al., 1979; Desert USA, 1996)

Males live only a couple of months after reaching maturity. Females can live up to a year after reaching maturity. (Desert USA, 1996)

Western black widow spiders spin webs that do not take on a definite shape or form. The webs vary in location, but more so in appearance. The silk that creates the web is made up of a liquid from the large abdominal glands. The glands open on the surface of the black widow's abdomen at the spinnerets. As the silk comes outside of the abdomen, it solidifies becuase of the stretching. Black widow silk is stronger than any other arachnid's.

These spiders are shy and nocturnal, and usually stay hidden inside of the web unless frightened. The belly is always facing the upward position. If a black widow is hidden inside a shoe, for example, and a person puts his/her foot inside of the shoe, the black widow will most likely bite. Females are not agressive, but will bite if disturbed.

These spiders produce a potent venom to which humans react, although the incidence of death from a black widow bite is actually quite small. (Desert USA, 1996; Jones, 1991; Virtual Science Centre, 1996)

Western black widows are like most arachnids in that they feed primarily on insects. Because of sticky substances in the silk of a web, black widows are able to catch their prey. The web is made of coarse silk.

The diet of L. hesperus includes beetles, cockroaches, and flies. Black widows kill by means of very small, hollow fangs through which they inject a poisionous venom into their prey. Black widows make small punctures all over the body of their prey, and then proceed to suck out the liquid contents. Because the black widows only take food in the form of liquid, the insect is not fully digested. However, digestive juices of the spider are injected into the insect prey, helping to make more of the prey item edible to the spider. Black widows leave behind the external skeleton of prey insects. These empty shells can be seen near the spider's web. A female black widow may occasionally cannibalize males of the species after mating. (Bisacre et al., 1979; Desert USA, 1996)

Black widows are preyed upon by mud-dauber wasps. (Bisacre et al., 1979; Desert USA, 1996)

Black widow spiders can be dangerous animals. They have a poisionous venom that is fifteen times as toxic as a rattlesnake. When a spider bites, only a little bit of the venom is injected into the prey. Rattlesnakes are considered more dangerous becuase when they bite, more of the venom is injected into their victim. However, it is important to note that if a large amount of the venom created by the black widow were to get into a human, that person would most likely die. In spite of this, most bites are not fatal. The bite of the black widow is more likely to be painful, and it can cause internal problems. Such side effects include abdominal pain as well as swelling of the muscles in the feet. The more mild symptoms include dry mouth, increased sweating, and swollen eyelids. If a person younger than 16 or older than 60 is bitten, he/she might have to go to the hospital. Most times death from black widow bites results in people between these age ranges because of lung or heart failure. Healthy people who are bitten usually recover in two to five days with the proper care. When a person is first bitten, soap and water works well to clean the area, and one should also apply a cold compress on the bitten area. (Desert USA, 1996)

Black widow spiders are not really beneficial to humans except for the fact that they eat insects. Western black widows are often found around human habitations, which makes them a potential predator of pest insects. (Bisacre et al., 1979)

Latrodectus hesperus is not an endangered species. These spiders can produce large numbers of offspring, and people do not hunt them. (Desert USA, 1996; Jones, 1991)

The most well known species of the black widow spider is Latrodectus mactans. The latin name means "murderous biting robber." This species occupies most southern areas. Latrodectus variolus is found in extreme parts of southeastern Canada. They live throughout the New England states and parts of Flordia. Latrodectus bishopi is also called a red widow. Brown widows, Latrodectus geometricus, are found in tropical areas. When this spider bites, it is not as severe as the other species of widows. The subspecies Latrodectus mactans tredecimguttatus is also known as a European black widow. Redback spiders, Latrodectus mactans hasselti, are found throughout Australia and some Southeast Asian countries.

When a woman's husband dies, she is called a widow. These spiders receive their common name, "widows" because females sometimes kill their mates. (Jones, 1991; Vest and Eagle Rock Research, 1999)