Butterfly Houses

I hear a lot of talk about butterfly houses. Do butterflies actually use them, or do they just make nice garden decorations?

—Pat Cluney, Des Moines, Iowa

George: Butterfly houses are primarily for decoration because the kinds of butterflies that frequent gardens don't use houses for shelter or roosting.
However, there are woodland species of butterflies that might use the houses, such as mourning cloaks and common wood nymphs, which overwinter in the protective cover of wood piles and tree cavities.