Choose a non-leaded exterior oil-based paint for use on your butterfly house. You can also paint it with an exterior latex paint, but the oil-based paint is water resistant, which helps to protect the wood from moisture.
Paint the entire butterfly house one color first. Pick a bright color that stands out against the environment. Red, yellow or orange are good color choices.
Make the roof a different, complimenting color if you wish. For example, you could paint the house yellow and give it a green roof.
Add colorful flowers to the exterior walls of your butterfly house. This not only makes the house more attractive, but it is possible the butterflies may see the flowers and come to them looking for nectar. After finding the house, they might decide to stay and rest for awhile.
Finish your design by painting leaves and branches around the flowers. Another nice touch is to paint green leaves on the bottom of the butterfly house. Then when you stand below it and look up, the house blends into the trees or bushes that you have the have the house hanging in.
Allow the paint to dry thoroughly before hanging it out for the butterflies to use. If you hang the butterfly house while the paint is wet, dirt and debris sticks to the wet paint.