The girl can't help it when a tasty male comes along.

VORACIOUS female spiders just cannot help trying to eat suitors before sex. Why? It's their aggressive personalities.

Females of several spider and mantis species dine on their partners, but only after acquiring the sperm necessary to fertilise their eggs. By providing his mate with a good meal, the male increases his own reproductive success. But that doesn't explain the behaviour of females that opt for dinner instead of sex, as fishing spiders (Dolomedes triton) often do. "Eating your mate during or after copulating, that's no big deal. Eating your mate beforehand, that's weird," says Chadwick Johnson at the University of Toronto, Canada.

Even aggressive females do get to mate if their suitors escape their fangs. But Johnson and Andrew Sih at the University of California, Davis, think the behaviour is part of a "voracity syndrome". They watched 60 female fishing spiders when males approached, and in encounters with predators and prey.

Femmes fatales who made the most attacks on males also showed the most frenzied feeding, and were most daring against predators. This, says Johnson, suggests these traits are linked, akin to human personalities (Behavioral Ecology and Sociobiology, DOI: 10.1007/s00265-005-0943-5).

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