Rick Kimpel via Flickr
When the “ick” factor is removed, most people recognize that spiders are a part of nature and help reduce insect populations. Louisiana’s most venomous spiders, the brown recluse (Loxosceles reclusa) and the black widow (Latrodectus mactans), need not occupy too much of your time with terror, but some caution is recommended.
The truth is the black widow spider is one scary arachnid—at least the girls are. Only the female is fatal; the males and spiderlings (baby spiders) blessedly aren’t. The adult female black widow spider is the most venomous spider in North America; its venom is fifteen times stronger than that of a rattlesnake. Adding to her notoriety, the female black widow spider has been known to eat the male after mating, hence the name “widow.” Scientists believe the female views the male as a source of protein, which is required for egg development. This type of behavior, sexual cannibalism, is actually uncommon in black widow spiders in the wild, but that hasn’t stopped it from becoming a big part of the spider’s persona.
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Black widows are easy to recognize. Just look for the shiny black spider with a red hourglass marking on the abdomen. Once on their webs, the spiders hang upside down waiting for insects and their abdomens are visible. The bright red markings send a warning to possible predators that the black widows are toxic and not a good meal. Black widows can be found in underground tunnels, under rocks, in woodpiles, inside open air toilets, and in dark and dry places such as garages, basements, barns, and storage sheds. In Louisiana, the black widow’s cousin, the brown widow spider (Latrodectus geometricus) has become more common throughout the state. Thought to be a native of Africa, the brown widow spider is brown with an orange or yellowish hourglass on the abdomen. While venomous, the brown widow spider is considered mild compared to its American relative.
Female black widows have poor eyesight and build webs to “see.” Their silk is the strongest of all spiders’. They build a web that is irregularly shaped and tangled-looking, often in a corner. The lines running into the center of the web bear sticky droplets, and the female can sense the vibration when an insect touches it; these webs catch beetles, flies, grasshoppers, moths, caterpillars, and other spiders for dinner. Knowing he may be on the menu, the male black widow will cut and rearrange the female’s web, so that she won’t know what’s happening as he carefully approaches her to mate.
This type of behavior, sexual cannibalism, is actually uncommon in black widow spiders in the wild, but that hasn’t stopped it from becoming a big part of the spider’s persona.
Black widows can lay up to four hundred eggs at a time and will protect their egg sacs. Since the young are known to cannibalize each other, not many will not make it to maturity. Almost entirely white upon hatching, widow spider nymphs darken with each molt.
Black widows only attack humans when threatened. Over two thousand black widow spider bites are reported in the U.S. every year, but death is rare; luckily, the females only inject a small amount of venom, and some bites are even dry, with no venom injected. The National Institute of Health reports that fatalities typically occur among the elderly, young children, and those who are very ill. Many bite victims don’t even realize they were bitten and only experience mild symptoms, but some bites can be very painful, with symptoms lasting three to five days and including nausea, abdominal and muscle pain, muscle rigidity, sweating, hypertension, and difficulty breathing. Most hospitals carry antivenom to alleviate these symptoms.
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The largest number of black widow bites occurred in the days of outhouses, before the advent of indoor plumbing. Black widows like to set up house under the seats of outdoor privies, where the smell attracts many flies and bugs for them to catch. A 1944 case study published in the Annals of Surgery reviewed twenty-four black widow bite cases, and sixteen of the twenty-four victims were bitten while on the pot. Twelve bites were on the genitals, and four were on the buttocks.
The female black widow is not without enemies herself. She is a favorite food of the praying mantis, and there are wasps that sting and paralyze too before eating. There are some birds that eat the widow, but they end up with an upset stomach.
Black widows are shy creatures; however, if disturbed they can be very aggressive and move quickly. If you see this itsy bitsy spider, it’s best for you to run up the water spout.
