female reproductive organ

When a male spider of the species G. cancriformis goes a-courtin', it's in his evolutionary interest to choose a virgin. That's because a female's first mate almost always gets to fertilize her eggs, while subsequent males wind up with nothing to show for their ardor. Which made Todd Bukowski, an evolutionary biologist at the University of Arizona at Tucson, wonder: How good are these male spiders at spotting virgins?