DENVER (KDVR) — Every fall, male tarantulas will travel up to 20 miles across southeast Colorado to find a mate. While thousands participate in the “mate-gration,” around one-third of them won’t survive the mating season, and it’s partly because females eat them.

FOX31 spoke with Sara Stevens, the director of animal collections at the Butterfly Pavilion, who explained that the life span of female tarantulas is much longer than males — regardless of if they eat the males or not.

Male tarantulas’ life span revolves around their mating period. When male tarantulas become sexually mature, they use courtship behaviors to tap on a female’s burrow, almost like knocking on her door. If she’s interested, she’ll tap back. If she doesn’t think he’s a viable option, she may try and make him a snack, said Stevens.

“So, it’s a little bit of a perilous situation if you’re the male. It might be the ‘Bachelor,’ it might be Grubhub, depending on the female,” said Stevens.

Assuming males survive the courtship, they’re still not in the clear. If a female mates with a male, they may still decide to eat them after.

“That seems like a pretty bad deal for the male until you realize that he’s already passed on his genetic material. And her getting a really good meal that’s really high in protein and energy is going to help her make the best possible eggs. So, it increases the chance of those offspring being successful,” said Stevens.

If the male survives mating, it will go on to mate with others. But it’s still on borrowed time.

Once males are sexually mature, they’re unable to molt out of their exoskeleton, which is how it traditionally grows. When that happens, males have about a year to a year and a half. When it comes to females, they are able to reproduce again and live for decades, according to Stevens.

The tarantulas are trekking through southeast Colorado at the end of August through early October. While you may not see thousands, you might be lucky enough to spot a couple while they’re in their mating season.