Along with plants, there are other ways to attract butterflies to your garden.
Most butterflies eat (actually, they sip) nectar from plants. But for some butterflies that do drink nectar, their favorite food is overripe fruit, tree sap, rotten fruit, or animal scat (dung). For instance, the Question Mark butterfly is one of the butterflies that prefer tree sap, overripe fruit, or scat over nectar-bearing flowers.
A variety of commercial butterfly feeders are available for purchase in many garden gift shops. You fill them with your homemade nectar and wait for the butterflies to arrive.