2. Classic Cedar Slat Hibernation Box
If you want the traditional look, this is it. A cedar slat box mimics the tight crevices butterflies seek out behind loose tree bark, and the natural oils in cedar help it hold up to weather without a chemical finish.
Materials: one cedar fence board (six inches wide), a scrap of ¼-inch plywood for the back, exterior screws, wood glue, a jigsaw or hand saw, a drill, sandpaper, and a small hinge or hook for the front panel. Cut two side pieces, a roof with an overhang, and a front panel.
Stack five or six slats inside the box, spacing them roughly ⅜ inch apart. Those gaps are the whole point. Butterflies slide into narrow vertical openings and feel secure; a box with a wide open cavity stays empty. Cut the front panel so it covers the top two-thirds of the opening, leaving the bottom third as the entry. Sand the interior slats so they’re slightly rough, not splintery.
Time: 1½ to 2 hours. Difficulty: intermediate. Mount it with the entry facing south or southeast. If you live somewhere with harsh winters, a box like this gives mourning cloaks and commas a place to wait out the cold.
💡 Pro Tip: Never stain or seal the inside of a butterfly house. The fumes linger, and butterflies are sensitive to them. If you want to protect the exterior, use an untreated linseed oil on the outside only, and let it cure fully before mounting.