We have a plant that is some sort of magnet for caterpillars.
We pulled approximately 42 caterpillars off of the plant and added them to my smallest child's bug house. He kept them in his room, periodically adding leaves so they had enough to eat. Eventually, the caterpillars went into cocoons.
Today, we noticed five of the cocoons had opened and five beautiful butterflies had emerged! It was raining hard that day, but my littlest decided it was best to let them out to spread their wings. It was a beautiful sight to see! We still have another 37 to go!