Beetles are like all insects, they have a head, thorax, and abdomen, and six legs. Their bodies tend to be very solid and tough. They have chewing mouthparts and often have powerful jaws. Adult beetles have modified wings: the first pair of wings is small and very hard, and acts as a protective covering for the second pair of wings. Many beetles can fly with their second pair of wings. Most adult beetles are brown or black, but some are very brightly colored. Beetle larvae look sort of like worms, but they have six legs and a hard head. Beetle pupa can't move and are covered with a leathery skin.
Beetles are the most diverse group of insects. There are over 300,000 species known to science, and probably many tens of thousands more still unknown. Beetles are found on land and in fresh water all over the world.
Beetles are found in just about every habitat. Most species live on plants, others tunnel or burrow, some swim.
Beetles have four different stages in their life cycle. Adult female beetles mate and lay eggs. The eggs hatch into a larval stage that is wingless. The larva feed and grow, and eventually change into a pupal stage. The pupa does not move or feed. Eventually the pupa transforms into an adult beetle.
Female beetles usually lay dozens or hundreds of eggs. Reproduction is often timed to match the time of most available food.
Adult beetles mate, and the female lays eggs on or very near a food source for her larvae. Some beetles collect a supply of food for their larvae, and lay the egg in the ball of food. Some scavenger beetles even feed their babies.
Most beetle species complete their lives in a single year. Some, especially larger ones, live for more than a year, hatching in summer, a few months to a year or more as a larva and pupa, and then emerging to reproduce as an adult.
Most beetles are active at night, but some are active in daylight (especially if they have chemical defense). Often they time their growth and reproduction so all the adults emerge at once, and for a short time you can find lots of a particular species.
Most beetles communicate with other beetles with chemicals. Males often locate females by their scent. Beetles usually can't see very well. Some beetle make sounds, usually scraping their mouthparts together or rubbing their legs on their bodies. Some beetles that live in dead wood drum and make vibrations. "Fireflies' and "lightning bugs' are actually beetles. They glow in the dark to communicate.
Beetles eat all kinds of food. Most are specialists in few kinds, but some, like ground beetles, eat lots of things. Most beetles eat plant parts, either leaves or seeds or fruit or wood. Many are predators on other small animals. Some eat fungus, and there are a bunch of species that eat dung. Sometimes the larvae eat different foods than the adults do.
Most beetles hide, and many beetle larvae dig tunnels to hide in. Some rely on their hard shell. Some, like lady beetles, have toxic chemicals to repel predators. Some can bite. Some, like ground beetles, run fast.
Beetles have lots of roles. Dung beetles help get rid of waste, beetles that eat wood help break down dead trees, some beetles feed on pollen and help pollinate flowers.
Beetle species are important pests because some of them eat our food. Some eat fruits or vegetable or other crops in the field, and others eat them in storage. Farmers have to spend lots of money and energy protecting their crops from beetles. Some beetles tunnel in wood, and these can kill or damage trees, or damage things we make from wood, like furniture, or even houses!
Some beetle species are important predators of pests, and others do valuable clean-up jobs, getting rid of dung and breaking down dead plants. A few species are now being used to eat problem weed plants as well.
Most beetle species are abundant, and don't need to be especially conserved. Beetles that live in habitats that are getting changed or wiped out could be in trouble, and some beetles depend on certain plant species. If the plant goes, they go. There is a species of aquatic beetle that only lives in a few rivers in northern Michigan. It is considered endangered.
The heaviest insects in the world are beetles. There are some African and South American beetles that are as big as your fist!