There doesn’t need to be any knowledge involved. It happens, because it works. Neither the beetle nor evolution itself “know” anything about quantum physics. The beetle is just a beetle and evolution is not even an entity that has any agency, it’s just a process that’s happening and that leads to remarkable results over time.

This is just one more example for the old discussion how complexity can develop through evolution. The classic example is the eye of vertebrates. Read up on that, if you’re interested in that discussion.