Because of their interactions with plants and other animals, butterflies play an important role in the web of life.
Butterfly caterpillars are voracious plant-eaters, yet they play an important role in plant survival. It has been estimated that arthropods—the large group of animals that includes all insects—consume 20 percent of the earth's vegetation each year. By chewing and digesting leaves, caterpillars cycle nutrients and energy through the ecosystem, making valuable sources of nutrition available to other plants and living organisms.
In turn, adult butterflies and caterpillars are food for many predators, including other insects, songbirds, mice, lizards, turtles and spiders. Butterflies are the primary food source for some wasps and flies, whose tiny larvae hatch within butterfly eggs, caterpillars, or pupae and feed on their host.
Because butterflies are sensitive to environmental change, scientists look to them as signals that indicate the health of the environment. Many butterflies are closely linked to specific plants and habitats, so an increase or decrease in their diversity tells us about the changing quality of a place and the impact of that change on other animals.