Male Widow Spiders Survive Sex by Mounting Immature Virgins

By Mindy Weisberger, Senior Writer | September 22, 2016 07:20am ET 

 

For some species of spiders, mating comes with a deadly risk — the possibility of being eaten by their much larger female partner. But in two species of widow spiders — the venomous spider group that includes black widows — males deploy an ingenious strategy to avoid being cannibalized during sex, according to a new study.

Scientists recently discovered that widow spider males Latrodectus hasselti and Latrodectus geometricus prefer to mate with females that are not yet sexually mature but which still have internal structures that are capable of storing sperm, which the males access by piercing the female's exoskeleton.

This sexual sneak attack is a win-win situation for the male. He literally plants the seeds to successfully fertilize the female at a later date, and is able to scuttle away from the encounter with his dignity — and his head — intact. 

Sexual cannibalism is common in widow spiders, but males mating with immature females to avoid being cannibalized is behavior that was previously unheard of, the researchers wrote in a new study.

Study co-author Maydianne C. B. Andrade, a professor in the Department of Biological Sciences at the University of Toronto, Scarborough, has studied widow spiders for nearly two decades, but had never observed this behavior until recently. She told Live Science in an email that it was first brought to her attention by a member of her research team — M. Daniella Biaggio, the study's lead author.

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