Coleoptera means “sheath wings,” a reference to the hardened forewings which cover the insect’s body. Most people can easily recognize members of this order – the beetles.
Beetles comprise nearly a quarter of all the described species on Earth. Over 350,000 species are known worldwide. The order is subdivided into four suborders, two of which are rarely observed. The suborder Adephaga includes ground beetles, tiger beetles, predacious diving beetles, and whirligigs. Water pennies, carrion beetles, fireflies, and the beloved lady beetles are all members of the larger suborder Polyphaga.
Beetles have hardened forewings, called elytra, which protect the delicate hindwings folded beneath them. The elytra are held against the abdomen at rest, meeting in a straight line down the middle of the back. This symmetry characterizes most members of the order Coleoptera. In flight, a beetle holds the elytra out for balance, and uses its membranous hindwings for movement.
Beetles feeding habits are widely varied, but all have mouthparts adapted for chewing. Many beetles are herbivores, feeding on plants. The Japanese beetle, Popillia japonica, causes heavy damage in gardens and landscapes, leaving skeletonized leaves on the plants it devours. Bark beetles and borers can do considerable damage to mature trees.
Predatory beetles attack other invertebrates in the soil or vegetation. Parasitic beetles may live on other insects, or even mammals. A few beetles scavenge decaying organic matter or carrion. Dung beetles use manure as food and to shelter developing eggs.
Habitat and Distribution:
Beetles are found worldwide, in virtually all terrestrial and aquatic habitats on Earth.
Major Families and Superfamilies in the Order:
- Carabidae – ground beetles
- Dytiscidae – predacious diving beetles
- Scarabaeidae – scarab beetles
- Elateroidea – fireflies and click beetles
- Coccinellidae – lady beetles
- Tenebrionoidea – blister beetles and darkling beetles
Families and Genera of Interest:
- Bombardier beetles, genus Brachinus, spray hot quinines when threatened, with visible puffs of smoke.
- Cotalpa lanigera, the goldsmith beetle, starred in a short story by Edgar Allen Poe, The Gold Bug.
- Glowworms (family Phengodidae) are not worms at all - they're beetles! Mature females retain their larval form, and glow between their body segments, appearing like a glowing worm.
- The invasion of the Asian Long-horned beetle, Anoplophora glabripennis, caused the preemptive removal of thousands of trees in New York and New Jersey. The beetle was introduced from Asia in 1996, arriving in wooden crates and pallets.
- Insects: Their Natural History and Diversity, Stephen A. Marshall
- Kaufman Field Guide to Insects of North America, Eric R. Eaton and Kenn Kaufman
- Garden Insects of North America, Whitney Cranshaw