This is my first year planting for and fostering Butterfly Caterpillars. I have brought them all inside and use big plastic totes with screen tops and the big mesh pop up hampers to house them. We've enjoyed having them inside where we can watch all the happenings.
My son has offered to build me a big butterfly house, which would sit in the shade on the deck. There are some advantages for me in having a big outside house. He will build the floor at a height where I don't have to stoop or bend to watch, clean or feed. It will have a big floor space, a tall interior with a big access door which will allow me to rotate in and out pots of fresh milkweed and window screening which would allow for fresh air. Our summers are generally quite hot and humid. The deck has a permanent shaded area or I could place it where it would get some sun, whichever is best.
I worry about something getting to them if they're outside. As long as the screen is commercial window screen and we have a good seal on wood to wood and wood to screen, should they be safe from wasps, spiders and those flies that damage the little cats? If so, then the only other thing I can think of right now would be ants. We don't have much of a problem but occasionally do see little ants on the deck railing.
He's ready to begin planning for the materials but I ask him to wait until I had some opinions from veteran cat herders.
My thanks once again for all the helpful advice. So far we're having great success. The worst thing we've encountered is a low supply of Milkweed. Just had no idea how much these little guys can put away. Thanks to the kindness of a nice lady, so far we've managed. Next year will see far more milkweed plants in my garden!