Scarabs make up a diverse group of land beetles, with sizes that reach several inches long. Click beetles, of the family Elateridae, make clicking sounds when overturned on their backs. They live in rotting wood or leaf litter.
The Carabidae beetles, commonly called ground beetles, have long legs and glossy elytra, or wing covers. They live in Alaskan bogs and marshes. Many land beetles subsist on flowers and seeds. These include the bruchids, or pea and bean weevils. Their larvae survive inside legume seeds and often infest stored peas.
The Byturus unicolor, or raspberry fruitworm beetle, feeds on raspberry plants. Adult soldier beetles, named for their red, yellow or orange trimmings, prefer goldenrod and milkweed pollen. Longhorn beetles, from the family Cerambycidae, compose a vast group of wood-borers. These collectible specimens display bright colors on large bodies. They help to decompose dead and dying trees, but prove troublesome to commercial lumberyards.
Dytiscidae, the largest family of aquatic beetles, breed in small ponds or arctic pools. Called "diving beetles" because they dive underwater to feed on fish larvae and other organisms, the beetles frequently surface for air as they hunt. They grow to 1 inch in length and some have spots on their elytra.
Whirlygigs (Gyrinidae) skim the surface of streams and lakes. Their short, flat legs help them to glide far from shore. Whirlygigs congregate in groups and feed on dead or dying insects. They deposit their larvae on shoreline plants. Other species, such as the tiny minute moss beetles (Hydraenidae), live on the edges of streams and feed on periphyton, a mixture of algae and debris.
Ladybird beetles (Coccinellidae) provide a service by reducing populations of aphids and mites that destroy valuable crops. Less than ¼ inch long, ladybirds exhibit orange and black markings.
Checkered beetles, from the family Cleridae, feed on wood-boring beetles. They get their name from the brightly colored patterns on their backs. Rove beetles (Staphylinidae) prey on aphids, mites and bark beetles. Blister beetles produce a chemical that causes skin blisters. They feed on grasshopper and other eggs.
The spruce beetle, a brown beetle a quarter inch in length, infests several varieties of spruce trees. Over the past quarter century, they have destroyed around two million board feet of Alaska's lumber. Another spruce tree pest, the engraver beetle, is often mistaken for a spruce beetle. When engraver beetles infest a tree, they attract woodpeckers that further damage the host.
Cottonwood leaf beetles attack cottonwood, balsam, poplar and willow trees. These insects bear small orange markings on tiny black bodies. Although trees rarely suffer death from these beetles, they may become unsightly after a heavy infestation.