Many butterflies play important roles as flower pollinators, but most of the feeding in a butterfly’s life is done in the caterpillar stage. Nearly all butterfly caterpillars are herbivores, eating leaves, stems, flowers, fruits, and other parts of plants.
Butterflies play an important role early in the food chain, converting nutrients from plants into their own bodies, which then become food for other animals. Usually, only a small fraction of butterfly eggs survive to become adult butterflies.
A wide variety of predators are ready to consume a butterfly during all stages of its life — egg, caterpillar, chrysalis, and adult. Butterfly predators include spiders, predaceous insects, fish, amphibians, reptiles, mammals, and birds.
Butterflies are also eaten by parasitoids. Parasitoid insects are usually wasps or flies that lay their eggs on (or in) butterfly eggs or caterpillars; the parasitoid larvae hatch and eat the caterpillar from within.
Elaborate camouflage, and deceptive eyespots, false antennae, and warning colors are ways that butterflies deter or deflect their predators.
Several types of butterflies eat toxic plants as caterpillars and therefore become toxic themselves. These species typically have distinctive bright colors, which predators — sickened once or twice — learn to avoid. Monarchs, which eat milkweeds, are an example. Then, other species, which may not be toxic at all, can have colors that mimic the toxic species, and gain some protection from “educated” predators. Warning systems can develop in which a number of toxic, distasteful, or perfectly edible species develop the same warning coloration. For example, several swallowtails in Missouri mimic the black coloration of the acrid-tasting pipevine swallowtail.