I wish we could release fireflies. I have a swarm at home, but it's depleted right now. I have several half-full jars. If I could just release the fireflies from the half-full jars I have, I'd have a full swarm again and could catch them and get a full jar.
But, as it stands, it uses up 60 energy every time I try to release them, and I end up re-catching half of them anyway - and end up with a half-full jar again.