One of the goals of this catalog is to provide much of that information. Just plant the right type of plants in the places that you want the butterflies to visit. The same is true for butterflies. If you grow the right plants in an area where butterflies can visit, then they will come. And since butterflies tend to remember the locations of desirable plants, they will visit more frequently and stay in the vicinity longer than if you offer the wrong plants.
Female butterflies use hostplants to lay their eggs upon.
These hostplants serve as food for the caterpillars that hatch from the eggs. Butterflies are extremely picky when it comes to laying eggs and will frequently lay their eggs on only a few species of closely related plants. The Monarch, for example, will only lay its eggs on members of the Milkweed family. Since milkweeds are found throughout much of the United States, Monarchs usually have little trouble finding a suitable hostplant on which to lay their eggs. The eggs hatch into small caterpillars, which grow as they consume the milkweed plant.