beetle

Beetle is any insect of the order Coleoptera, the largest known order of animals. Beetles inhabit nearly every terrestrial and freshwater habitat and range from a few millimeters to several centimeters in length. They are highly diverse, with hundreds of thousands of described species and many more likely undiscovered.

A defining feature is the pair of hardened forewings, called elytra, that cover the flying hind wings and protect the abdomen. The elytra meet along a straight suture down the middle of the back. Beetles have chewing mouthparts and undergo complete metamorphosis: eggs hatch into larvae (grubs), which then become pupae before emerging as adults. This life cycle results in distinct larval and adult forms.

Diversity and ecology: Beetles occupy a wide range of niches, including herbivores, predators, scavengers, and some pollinators. They feed on plants, wood, fungi, dung, or dead matter, and many active species are important in nutrient cycling and pest control. Some beetles are aquatic or semi-aquatic. Notable groups include lady beetles (Coccinellidae), ground beetles (Carabidae), scarabs (Scarabaeidae), and weevils (Curculionidae).

Distribution and evolution: They are cosmopolitan, found in almost every environment on Earth. The group is ancient, with fossils dating back to the Permian period, and many modern lineages diversified after major plant radiations, contributing to their extraordinary diversity.

Human relevance: Some beetles are agricultural pests or stored-product pests, while others are beneficial predators of pests or important decomposers. Beetles also appear in science and culture as subjects of study in evolution and development. Conservation concerns include habitat loss and pesticide exposure, which threaten specialized or localized species.