Insects have been part of the earth's ecology since the last 250 million of years, and constitute the largest and most diverse group of animals on the planet, with about 1 million species, meaning 80% of all animal species. They play very important roles in earth's ecosystems, such as soil turning and aeration, dung burial, pest control, pollination and wildlife nutrition. Beetles, for example, are scavengers that feed on dead animals and fallen trees and thereby recycle biological materials into forms found useful by other organisms.  They also act as biological control of other species and are also essential to vital processes, like pollination.