 Butterflies are delicate, but they're also tough. And this week, we're understanding a bit more about how tough they can be. We've long known that monarch butterflies are champion flyers. They migrate every year from North America to central Mexico. Their journey is multigenerational, so the butterflies that start the trip aren't the ones that complete it. But new research indicates that another butterfly, the painted lady, can travel across the entire Atlantic Ocean in one go without stopping.