Why do butterflies lay their eggs in garbage?

Most butterflies don't lay their eggs in garbage. They typically lay their eggs on the plant that their caterpillars will feed on. Monarchs butterflies lay their eggs on milkweed plants. Spicebush swallowtails butterflies lay their eggs on Spicebush, Sassafras, Sweet Bay, and Prickly Ash. You get the idea. I don't know of any butterflies that lay their eggs in garbage, but if they do it is probably the type of garbage that their caterpillars would feed on.