Numbers of species. Beetles (Order Coleoptera) are known to include some 350,000 described species. In the United States, there are nearly 30,000 kinds of beetles known. These figures are rising constantly due to the naming of new species by taxonomists.
Size. Beetles vary from species that are barely visible (especially the Feather-winged beetles), to large tropical species that are the size of a human hand. Titanus giganteus, a long-horned beetle from South America, is usually considered to be the largest known beetle.
Food. Beetles are such a large, diverse group that they have representatives that eat nearly every kind of food. They feed on all parts of living or dead land plants. Some are excellent hunters and predators. Some are scavengers and a few are parasitic.
Habitats. Habitats of beetles on land are numerous. Many are on the ground or under material on the ground. Different kinds can be found on vegetation, in rotting wood or plants, in carrion, fungi, and dung. Some are aquatic, living in bodies of water that range from small puddles to cold mountain streams, and a few are parasitic. They are found in dry deserts and in the cold temperatures of mountain tops.