Western black widow
Western black widow (Photograph by Paul Ollig/NPS)

Why do black widows eat their mates? Is there an evolutionary advantage?

The Wild File: Black Widows

Western black widow
Image

A. They don’t at least, not with any more enthusiasm or frequency than other arachnids. Like most spiders, the black widow is a web builder, and the females are larger than the males. Also like most spiders, widows are predators that eat only living things. (Hence their much-fussed-about poison, a neurotoxin that can cause mild paralysis in mammals, including some humans.) So if a male comes poking around the web at mating time and his lady is hungry, there’s a chance he’ll provide her with more than sperm. If the male scores a well-fed widow, he’ll probably escape. An exception to this rule: the Australian redback, a member of the black widow genus. The male redback has developed a taste for rough, sacrificial sex, flipping his bare abdomen into the hungry female’s mouth during mating. Researchers at the University of Toronto discovered why: A male who offers himself to his mate scores more time in the sack, increasing his chances of passing on genes.

Western black widow

Western black widow Western black widow

From Outside Magazine, April/May 2021
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Lead Photo: Photograph by Paul Ollig/NPS
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