homepage logo

Living Sanibel: Black Widow Spider

By Staff | Nov 8, 2013

Black Widow. Lorraine Sommers.

This is the one spider you probably do not want to look for. Females are aggressive and will inject a potentially lethal neurotoxic venom into the bite that can result in death. Sixty-three confirmed deaths were reported in the United States between 1950 and 1959. Improvements in anti-venom have significantly reduced this mortality rate but the black widow, worldwide, is considered to be one of the most dangerous spiders on earth. They are easy to recognize by their shiny black bodies and distinctive red hourglass markings on their rounded abdomen.

The female black widow is aptly named. The local species, Latrodectus mactans, is the only known black widow that practices sexual cannibalism. Shortly after the male mates with the female, she turns on him, killing him with her powerful venom, then consumes him. Not all pairings result in this bizarre ending, and males that manage to escape can go on to fertilize other black widows, if they dare!

Female black widows are very fertile, laying four to nine egg sacs per year with each sac containing up to 400 eggs. In keeping with the temperament of their mother, the juvenile spiders practice paternal cannibalism and only a few of them make it to maturity. Black widows feed on woodlice, other spiders and a wide variety of insects. They are in turn preyed upon by preying mantis, spider wasps and a number of specialized flies. If you happen across a black widow do not attempt to pick it up or get too near it. They are fast and aggressive and if you are bitten by one you MUST SEEK MEDICAL ATTENTION IMMEDIATELY!

-This article is an excerpt from Living Sanibel-A Nature Guide to Sanibel & Captiva Islands by Charles Sobczak. The book is available at Barnes & Noble, all Island bookstores, Baileys and your favorite online sites.