Kinds of Beetles
Beetles make up the order Coleoptera. The most important families commonly found in the United States and Canada include the following:
Ambrosia Beetles and Bark Beetles (family Scolytidae). Small, cylindrical bodies. Bark beetles burrow into cambium (the layer of cells just under the bark of trees and shrubs), where they lay their eggs and feed on cambium and bark. Ambrosia beetles burrow into heartwood, where they lay their eggs and feed on a type of fungus that grows there. The tunnels of bark and ambrosia beetles are harmful to trees; these beetles also spread disease from tree to tree.
Blister Beetles (family Meloidae). Long, soft bodies. The body contains an oil that can cause a painful blister if it comes in contact with human skin. A number of species feed on garden and crop plants.
Bostrichid Beetles (family Bostrichidae). Bore into twigs and branches, where they feed.
Carpet Beetles (family Dermestidae).
Carrion Beetles (family Silphidae). Club-shaped antennae; legs adapted for digging. A common species is the sexton beetle (Necrophorus marginatus). Two sexton beetles will bury the entire carcass of a small bird or mouse in a few hours. The female lays eggs in a tunnel leading to the body, and both young and adults feed on the carcass.
Checkered Beetles (family Cleridae). Cylindrical bodies covered with hairs. Checkered patterns of color on forewings. Most prey on larvae of bark beetles.
Click Beetles (family Elateridae).A click beetle throws its body into the air with a snapping movement.
Cucujid Beetles, or Flat Bark Beetles (family Cucujidae). Long, flat, small. Live under dead bark of trees. Most feed on mites and small insects.
Darkling Beetles (family Tenebrionidae). Hard-shelled with oval bodies. They live under rocks or loose bark and feed at night on dead or living plants. Some eat stored grain. The mealworm (Tenebrio molitor) is bred and sold as food for insect-eating pets.
Deathwatch Beetles (family Anobiidae).
Diving Beetles (family Dytiscidae). Flat, oval bodies that are dark and shiny. The beetles hang head downward from the surface of quiet ponds, waiting to catch insects. By holding a supply of air under their wing covers, they can breathe under water.
Desert beetles dive into the sand to keep cool. Diving beetles dive into the water to hunt for snails, tadpoles, and small fish.
The diving beetle is one kind of water beetle that lives in ponds and streams. It has a long, oval body good for floating and diving. Its long legs move together like oars as it swims through the water.
A bubble of oxygen is trapped under its elytra or body hair when it dives. This allows the diving beetle to breathe underwater for a long time. The diving beetle sometimes hangs upside down in the water. This allows it to draw more oxygen into its body through openings between its elytra and abdomen.
Dried-fruit Beetles, or Pollen Beetles (family Nitidulidae). Small, flat bodies. Feed mainly on dried or rotten fruit. A few species are serious pests.
Fireflies (family Lampyridae).
Ground Beetles (family Carabidae). Long, flattened bodies. Fast runners. Ground beetles usually hide under stones during the day. They destroy harmful insects.
Hister Beetles (family Histeridae). Small, dark, shiny bodies. Live in or under cow dung, in decaying matter, or under loose bark. Prey on other insects.
Ladybugs, or Ladybirds (family Coccinellidae).
Leaf Beetles (family Chrysomelidae). Oval bodies. Feed on leaves. Some species, including potato beetles, are very destructive. Many species are beautifully colored; among these species are tortoise beetles, some of which are iridescent gold.
Long-horned Beetles (family Cerambycidae). The threadlike antennae are sometimes larger than the body itself. Feed on pollen, leaves, and bark. May ruin wood articles by tunneling through them.
Metallic Wood-borers, or Jewel Beetles (family Buprestidae). Metallic blue or bronze bodies; serrated antennae. Attack a variety of trees, including apple trees and other fruit trees.
Patent-leather Beetles, or Bessbugs (family Passalidae). Large, shiny, black. Live in rotting logs. Eat decaying wood. Make squeaking sounds when disturbed.
Powder Post Beetles (family Lyctidae). Reddish brown. Bore out the insides of wooden objects, which they reduce to a powder. Very destructive.
Rove Beetles (family Staphylinidae). Long and flat. Live on the ground and scavenge for food. Some species make their homes in ant or termite nests.
Scarab Beetles (family Scarabaeidae). Some species are among the largest of insects. Rhinoceros and ox beetles reach a length of two inches (5 cm) in North America.
Seed Weevils (family Bruchidae).
Sexton Beetles. See Carrion Beetles in this list.
Snout Beetles, or Snout Weevils (family Curculionidae).
Soldier Beetles (family Cantharidae). Resemble mostly fireflies. Typically feed on aphids and other small insects.
Spider Beetles (family Ptinidae). Tiny, dark-colored bodies. Typically feed on stored products.
Stag Beetles (family Lucanidae). Have long mandibles, or jaws, which often are branched like antlers. Stag beetles look fierce but eat only vegetable matter and honeydew.
Tiger Beetles (classified in the family Cicindelidae by some biologists; in the ground beetle family by others). Long legs and sharp, powerful jaws. Tiger beetles hunt other insects, which they grab in their jaws and bang against the ground to kill.
Like the big cat it is named for, the tiger beetle is a ferocious predator that eats other insects. But the tiger beetle’s larva is even more ferocious.
The wormlike larva lives in a burrow in the ground. It uses hooks to hang onto the wall of the burrow. Then it waits. When another insect comes close to the burrow, the larva attacks. It jumps out and sinks its jaws into its prey. Then it drags the helpless insect into its burrow and eats it.
Water Scavenger Beetles (family Hydrophilidae). Black or brown oval bodies; club-shaped antennae. Feed on decaying animal or vegetable matter.
Whirligig Beetles (family Gyrinidae). Black, oval bodies. Swarms of them are often found whirling about on the surface of lakes and streams.
When the whirligig (HWUR lee gihg) beetle sees prey, it spins around quickly to catch it. The whirligig beetle is another kind of water beetle. Its dark, oval body is well equipped to float. Its paddle-shaped hind legs help it skim and spin across the water.
The whirligig beetle has compound eyes that are divided in two. The upper half of each of its eyes sees on or along the water. The lower half sees underwater and looks for small fish and insect larvae to eat.
On a pond, you might see as many as a hundred whirligigs spinning around in zigzag patterns. But never once will one whirligig bump into another. A special organ in its antennae “picks up” echoes of sound waves bouncing off objects in the water. This helps the whirligig avoid collisions.