Butterflies in temperate climates spend the winter in diapause which is the hibernation state for insects. According to Butterfly Gardeners' Quarterly, butterflies can overwinter in any one stage, egg, larva, chrysalis or adult. A butterfly box, also called a hibernation box, offers these creatures a dry shelter for overwintering. While you can always purchase a butterfly box from a nature store, it is also possible to build one yourself.
Purchase an 11/16-inch thick sheet of wood such as red cedar, redwood and exterior plywood. These types of wood are naturally decay resistant.
Cut two wooden rectangles for the front and back of the butterfly box using a handsaw or a circular saw. The front piece should measure about 5 x 7 inches while the back should be about 5 x 6 inches.
Use a ruler and pencil to measure and draw six ½ x 3 inch slots on the front piece of wood. These will become the entranceways for the butterflies, at the same time helping to keep out mice and birds. Bore a hole on the end of each slot using a ¼ inch drill bit. Use a jigsaw to cut out each slot.
Cut two additional 5 x 7 sized wooden rectangles for the sides of the birdhouse. Cut a bevel in each rectangle at a 17-degree angle. Once you assemble the hibernation box, the bevelled edges will allow the roof to sit at an angle.
Cut a 5 x 5 wood square for the floor of the hibernation box and a 6 x 7 rectangle for the roof. Bore a small drain hole in each corner of the floor and a ventilation hole at the top of each side. Bore two 1/8-inch holes in the roof so that you can thread spool wire to hang the butterfly box upon completion.
Use wood glue, a hammer and nails to put the pieces of the butterfly box together. Place a few large twigs inside for the butterflies to rest on before adding the roof. Hang the finished project outside.