Include host plants in your garden to support the complete lifecyle of butterflies! Adult butterflies and moths (Lepidoptera) lay their eggs on plants, known as host plants, and the caterpillars that follow feed upon the plant as they grow. The link between Monarchs and milkweed plants is well known, but there are many butterflies that rely on native plants as larval hosts. Caterpillars are an important source of food for nesting birds, as well. It takes thousands of caterpillars to raise one brood of chickadees.