Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it is one of the 10 most species-rich animal families. They belong to the Adephaga. Members of the family are primarily carnivorous, but some members are herbivorous or omnivorous.
Ground beetle
A crucifix ground beetle (Panagaeus cruxmajor) got Charles Darwin into trouble in 1828.
A Brachinus species typical bombardier beetle (Brachininae: Brachinini) from North Carolina
A Lophyra sp. tiger beetle from Tanzania
Beetles are insects that form the order Coleoptera, in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 described species, is the largest of all orders, constituting almost 40% of described insects and 25% of all known animal species; new species are discovered frequently, with estimates suggesting that there are between 0.9 and 2.1 million total species. Found in almost every habitat except the sea and the polar regions, they interact with their ecosystems in several ways: beetles often feed on plants and fungi, break down animal and plant debris, and eat other invertebrates. Some species are serious agricultural pests, such as the Colorado potato beetle, while others such as Coccinellidae eat aphids, scale insects, thrips, and other plant-sucking insects that damage crops. Some others also have unique characteristics, such as the common eastern firefly, which uses a light-emitting organ for mating and communication purposes
Coleoptera at the Staatliches Museum für Naturkunde Karlsruhe, Germany
Titan beetle, Titanus giganteus, a tropical longhorn, is one of the largest and heaviest insects in the world.
Scydosella musawasensis, the smallest known beetle: scale bar (right) is 50 μm.
Hercules beetle, Dynastes hercules ecuatorianus, the longest of all beetles.