Beetles are insects of the order Coleoptera (pronounced /koʊliːˈɒptərə/; from Greek κολεός, koleos, “sheath”; and πτερόν, pteron, “wing”, thus “sheathed wing”), which contains more species than any other order in the animal kingdom, constituting about 25% of all known life-forms. About 40% of all described insect species are beetles (about 400,000 species), and new species are discovered frequently. Some estimates put the total number of species, described and undescribed, at as high as 100 million, but 1 million is a more likely figure. The largest taxonomic family, the Curculionidae (the weevils or snout beetles), also belongs to this order .
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. They often feed on plants and fungi, break down animal and plant debris, and eat other invertebrates. Some species 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 or cowpea beetle Callosobruchus maculatus, while other species of beetles are important controls of agricultural pests. For example, beetles in the family Coccinellidae (“ladybirds” or “ladybugs”) consume aphids, scale insects, thrips, and other plant-sucking insects that damage crops.