Very nice Bernard. Where did you find butterflies up there? I know your no closer to spring than I am. :-/
Far from Spring, although in a few weeks the Maple trees will be cut and sugar shacks will open.
I believe larvae are purchased from another country and the butterflies are born inside a green house, which is open to the public. We could see some cocoons while touring the place. Once the butterflies are "born" they are released inside the green house. It's an anual fesival of sorts.