For brown widow spiders, sex is literally a matter of life and death. If a male chooses an adult female, chances are roughly 50/50 that she’ll eat him afterward. But if he mates with a younger subadult female, she’ll let him live to see another day, Daily Mail reports. The curious thing is that despite the risk of death—and the fact that younger females are actually the ones that can pump out more spider babies—the males still prefer to copulate with older females. Scientists, writing in this month’s issue of Animal Behaviour, can’t explain the curious behavior, but think that older females may give off enticing pheromones that trick males into the dubious mating arrangement.