What Is a Beetle?

What makes a beetle a beetle? Here are some distinguishing characteristics that make these “little biters” different from other insects.

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by Anthony Davies, © Her Majesty the Queen in Right of Canada
The study of a superdiverse group of organisms such as beetles requires the close examination of a wide range of anatomical structures in order to recognize and classify species and larger groups correctly.

The English word “beetle” comes from the Middle English bityl or betyll and the Old English bitula, all of which mean “little biter.” Other commonly used names, such as “weevil” and “chafer” derived from Old English and Old High German, also relate to biting. Coleoptera, first coined by Aristotle in the fourth century bce and later adopted as an order of insects by Carl Linnaeus in 1758, is derived from the Greek words koleos, meaning “sheath,” and pteron, or “winged,” and was inspired by the tough elytra of beetles.

Distinguishing Features of Beetles

Among other adaptations, beetles are distinguished from other insects by their chewing mouthparts, the conversion of their forewings into hardened elytra, their hind wings that fold lengthwise and across beneath the elytra, and their holometabolous development. Holometabolous insects pass through four very distinct life stages: egg, larva, pupa, and adult. The larvae and adults frequently differ in habits and habitat, functioning in the environment as if they were two separate species.

Beetles, like other insects, crustaceans, arachnids, millipedes, centipedes, and their kin with segmented exoskeletons and jointed appendages (antennae, mouthparts, legs), are classified in the phylum Arthropoda. Light and durable, the beetle exoskeleton is incredibly tough and rigid or characteristically soft and pliable, and provides protection and support. It serves as a platform for important tactile and chemosensory structures externally, while providing an internal framework that supports muscles and organs. The exoskeletal surface is smooth and shiny, or dulled by waxy secretions or microscopic networks of cracks (alutaceous) resembling that of human skin. The surface is variously festooned with spines, hairlike setae, or flattened setae called scales, and sculpted with tiny bumps (tubercles), pit-like punctures, ridges, grooves (striae), or rows of punctures.

  • Published on Feb 6, 2015
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