They are just butterflies, you can't keep them forever. How would you like it, if I locked you in your room and didn't let you out?
They need to explore the world. You need to set them free.
You don't own them. They are a living thing. Your job was to look after them until they grew up and could look after themselves. You did so well. All 10 of your caterpillars have made it into butterflies. That is amazing. It is time for them to leave you now. If you are lucky they may come back and visit you. It is time to let them go and have adventures of their own.
And so we both shed a tear. Big man for the butterflies he had cared for and me because I knew I would need to convince myself of this one day when I have to let my butterflies explore the world. Fly high little butterflies.
And to both our joy, one of the butterflies did come back briefly to say thanks!