Beetles make up the most species-rich order of insects. The order’s scientific name, Coleoptera, means “sheathed wing”, and contains more described species in it than in any other order in the animal kingdom. Forty percent of all described insect species are beetles (about 350,000 species), and new species are frequently discovered. Estimates put the total number of species, described and undescribed, at between 5 and 8 million.
Beetles can be found in almost all habitats, but are not known to occur in the sea or in the polar regions. They interact with their ecosystems in several ways. On the one hand, they feed on plants and fungi, break down animal and plant debris, and eat other invertebrates. On the other hand, they are prey of various animals including birds and mammals. Certain species are agricultural pests, such as the Colorado potato beetle Leptinotarsa decemlineata, the boll weevil Anthonomus grandis, the red flour beetle Tribolium castaneum, and the mungbean beetle Callosobruchus maculatus, while other species of beetles are important controls of agricultural pests. For example, coccinellidae (“ladybirds” or “ladybugs”) consume aphids, scale insects, thrips, and other plant-sucking insects that damage crops.