whirligig beetle: see water beetle.

water beetle, name for aquatic beetles of several families. They should not be confused with water bugs, which are true bugs (order Hemiptera). The predaceous diving beetles (family Dytiscidae) are a large group, widespread in quiet streams and ponds. They are black, brown, or greenish, .08 to 1.57 in. (3-40 mm) long, with smooth oval bodies and hairy, oarlike hind legs. There is a cavity beneath the wings for holding an air supply, so the diving beetle can remain submerged for long periods; however, the insect often hangs head down from the surface, exposing the openings (spiracles) of the last two of its breathing tubes, located at the tip of the abdomen. Both the adults and the long, conspicuously segmented larvae prey on a variety of animals, including snails and fish much larger than themselves. Adults of most species are strong fliers, and many are attracted to lights at night. The water scavenger beetles (family Hydrophilidae), of similar appearance, are abundant in marshy places in warm parts of the world and feed on water plants and decaying matter. Their larvae are predaceous. The whirligig beetles (family Gyrinidae) are oval, shiny, blue-black to dark brown beetles, about 3/4 in. (19 mm) long. They are found in groups in sheltered places, spinning around on the surface of the water. They feed on small insects on the surface and seldom dive. There are several other groups of water beetles, all classified in the phylum Arthropoda, class Insecta, order Coleoptera.

snout beetle: see weevil.

scarab beetle or scarab, name for members of a large family of heavy-bodied, oval beetles (the Scarabaeidae), with about 30,000 species distributed throughout most of the world and over 1,200 in North America. North American scarab beetles range in length from less than 1/2 in. to more than 2 in. (5-50 mm); members of some tropical species grow several inches long. Many scarab beetles are brightly colored and many are iridescent. A large group of scarab beetles are scavengers, feeding on decaying vegetation or on the dung of grazing animals. Most of these lay their eggs in underground chambers supplied with dung, where the larvae feed and pupate, emerging as adults. These scarabs, called dung beetles, play an extremely important role in the rapid recycling of organic matter and the disposal of disease-breeding wastes. Australia, which has few native dung beetle species, has imported African species to help dispose of cattle dung. Some of the dung beetles, known as tumblebugs, form balls of dung that they roll about with their hind legs, sometimes for long distances and sometimes working in pairs. Eventually they bury the ball and lay eggs in it. One such ball-roller is the sacred scarab (Scarabaeus sacer), a black scarab beetle of the Mediterranean region. In ancient Egypt the periodic appearance of this beetle in great numbers on the surface of the Nile mud led men to associate the sacred scarab with resurrection and immortality. It was believed that all scarabs were males capable of reproducing their kind. Their ball-rolling activities were associated with the diurnal movement of the sun. Other species of scarab beetles feed on living plants. Members of these groups include such major crop and garden pests as the Japanese beetle, the rose chafer, and the June beetle (also called June bug and May beetle). Cockchafers are Old World species similar to June beetles. Adult plant-eating scarab beetles attack leaves, flowers, and fruits, while the larvae, which develop from eggs laid in the ground, attack roots. The largest scarab beetles in North America are the plant-eating Hercules beetles and their close relatives, the rhinoceros beetles and elephant beetles. In most species of this group the males are prominently horned. The Hercules beetles of the S United States may grow 21/2 in. (6.4 cm) long; their tropical relatives may attain a length of 6 in. (15 cm) including the horns. Despite their ferocious appearance these beetles are harmless to people. The term scarab is also applied to representations of scarab beetles made of stone, metal, or other materials. Finely carved scarabs were used as seals in ancient Egypt; inscribed scarabs were issued to commemorate important events or buried with mummies. Roman soldiers wore scarab rings as military symbols. Scarab beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Scarabaeidae.

potato beetle, name for two beetles of the leaf beetle family and for two of the blister beetle family, all destructive to the potato plant and its relatives. Most notorious is the Colorado potato beetle, or potato bug (Leptinotarsa decemlineata), a black-and-yellow striped member of the leaf beetle family. It was once confined to the Rocky Mts., where it lived on wild members of the nightshade, or potato, family. When settlers introduced the Irish, or white, potato (c.1855), the insect spread through most of the United States and then to Europe. Its orange-yellow eggs are laid in clusters on the undersides of the leaves, on which the reddish, black-spotted larvae feed. Pupation (see insect) takes place on the ground, and the adults emerge to feed on the potato plants; they hibernate underground during the winter. The destruction caused by the Colorado potato beetle has been one of the chief reasons for the development of insecticides; Paris green and other arsenic compounds have been used extensively. A member of the same family is the three-lined potato beetle (Lema trilineata) of the E United States, sometimes called old-fashioned potato beetle. The adults are yellow-orange with black stripes and lay their eggs scattered randomly over potato leaves. Two blister beetles of the genus Epicauta are also known as old-fashioned potato beetles. They are slender insects with complex life histories, passing through several larval stages before pupating. They feed on potatoes, tomatoes, and other members of the nightshade family. One (Epicauta vittata) has orange and black stripes and is also called striped potato beetle, or striped blister beetle; the other (E. marginata) is black with gray margins. The various potato beetles termed "old fashioned" were considered major pests before the spread of the more destructive Colorado potato beetle. Potato beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera. The Colorado potato beetle and the three-lined potato beetle are classified in the family Chrysomelidae and the old-fashioned potato beetles (Epicauta) in the family Meloidae.

oil beetle: see blister beetle.

ladybird beetle or ladybug, member of a cosmopolitan beetle family with over 4,000 species, including 350 species in the United States. Ladybird beetles are mostly under 1/4 in. (6 mm) long and are nearly hemispherical in shape, with very short legs. They are usually red or yellow with black spots, or black with red or yellow spots, the common species differing only in the number of spots. They have a bitter taste, and their bright coloration is thought to serve as a warning to predators. The name is believed to date from the Middle Ages, when these beneficial beetles were dedicated to the Virgin. Nearly all ladybird beetles, both larvae and adults, are predators on destructive, plant-eating insects. The eggs are laid on plants infested with aphids or scale insects, on which the larvae feed until they pupate in the remains of the last larval skin. The adults gather in large numbers in the fall, prior to winter hibernation, and are often collected at that time by farmers for use in pest control. The first outstanding demonstration of pest control by use of natural enemies occurred in the United States in 1889, when Australian ladybird beetles (Rhodolia cardinalis) were imported to wipe out the cottony-cushion scale, an insect that had accidentally been imported from Australia to California and there became a threat to citrus orchards. The Mexican bean beetle (Epilachna varivestis), which has spread through E North America, and the squash beetle (E. borealis) are the only North American ladybird beetles considered destructive. They are yellowish with black spots; adults and larvae feed on plants. Ladybird beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Coccinellidae.

dung beetle: see scarab beetle.

diving beetle: see water beetle.

click beetle, common name for members of the widespread beetle family Elateridae. Also called elater beetle, the click beetle has a hinge across the front of the body that allows it to flex, and a spine-and-groove arrangement on the underside of the body that provides a snapping mechanism. When a click beetle is turned on its back it cannot right itself by rolling onto its short legs. It arches its body upward so that only the ends touch the ground, then straightens suddenly, causing the spine to slide into the groove. This sends the beetle spinning through the air and produces a loud click. If the beetle lands on its back again it repeats the performance. A click beetle also snaps its body when it is picked up, which may cause the predator to drop it. Click beetles have long, flat bodies, generally rectangular, but curved at the ends. They range in length from 1/4 in. to 4 in. (6.4-102 mm); most are black or brown. Most adults are nocturnal leaf-eaters. The larvae, called wireworms, are destructive to a large variety of plants. Some tropical click beetles are brilliantly luminescent. Click beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Elateridae.

carpet beetle, name for several beetles that are highly destructive to carpets and upholstery and are classified in the same family as the larder beetles. Adult beetles of this family are pollen eaters, but the larvae feed on a variety of animal matter. The reddish to yellow-brown carpet beetle larvae feed on wool, fur, leather, and on plant fibers that are soiled with grease, doing more damage to household goods than the clothes moth. The adults, 0.08 to 0.2 in. (3-5 mm) long, solid black or black-and-white patterned, leave the house after emerging from the pupal stage. The larvae of the species commonly called larder beetles feed on meats and cheese; the larvae of other species in the family are pests in museums, feeding on dried insect collections. Carpet beetles are classified in the phylum Arthropoda, class Insecta, family Dermestidae, genera Attagenus and Anthrenus.

blister beetle, common name for certain soft-bodied, usually black or brown, mostly elongate and cylindrical beetles belonging to the family Meloidae. Blister beetles are common insects found feeding on the flowers and foliage of various plants. Occasionally some, e.g., potato beetles, become serious defoliating pests of potatoes, tomatoes, beets, asters, and other crops and flowers. The larvae are predacious or parasitic, feeding on the eggs of grasshoppers and of bees. Blister beetles undergo hypermetamorphosis, a complex life cycle with several different larval forms. The first of the six larval stages, called a triungulin, is a minute, active, and long-legged form that seeks out the host's nest; the following stages are grublike. Adults emerge in midsummer. One group of blister beetles has body fluids that contain cantharadin, a substance that can cause the skin to blister, from which the family gets its name. The Spanish fly (Lytta vesicatoria), a bright green or bluish blister beetle, is a common S European species from which cantharides are extracted and commercially prepared by crushing the wing covers (elytra) of the adults. This quite poisonous chemical is used medicinally as a skin irritant (in plasters), a diuretic, and an aphrodisiac. The lethal dosage for man is about .03 grams. Another group of meloid beetles has no cantharadin and is sometimes called the oil beetles because of the oily substance they secrete as protection against predators. Blister and oil beetles may be brushed into pans of kerosene or killed with systemic poisons or contact insecticides. Blister beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Meloidae.

beetle, common name for insects of the order Coleoptera, which, with more than 300,000 described species, is the largest of the insect orders. Beetles have chewing mouthparts and well-developed antennae. They are characterized by a front pair of hard, opaque, waterproof wings called elytra, which usually meet in a straight line down the middle of the back. The elytra cover the rear pair of membranous flight wings, protecting them and the body from mechanical damage and desiccation. Beetles are poor flyers compared with many other insects, but they are well adapted for surviving rigorous conditions. They are found everywhere except in oceans and near the poles, and they occupy nearly every kind of habitat. Most are terrestrial, but some are underground tunnelers and some live in water. These water beetles are often confused with water bugs, but the latter all have sucking mouthparts. Beetles range in size from under 1/32 in. (1 mm) to over 6 in. (15 cm) long; tropical species are the largest. Most are dull, but members of several beetle families are brilliantly colored, some with a metallic or iridescent sheen. The majority of beetles are plant eaters, but there are also many predators and scavengers and a few parasites. Many beetles are highly destructive pests of crops and gardens (e.g., Japanese beetle, potato beetle, boll weevil), but others are beneficial predators of harmful insects (e.g., ladybird beetles). The largest of the many beetle families is the scarab beetle family, with over 20,000 species; among these are the dung beetles, which are invaluable scavengers. Weevils are plant-eating beetles with mouthparts elongated into snouts bearing jaws at their ends. The fireflies are luminescent beetles. Blister beetles, including the so-called Spanish fly, produce irritating secretions. Beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera.

bean beetle, common name for a destructive beetle, Epilachna varivestis, of the ladybird beetle family. Although nearly all other members of this family are beneficial carnivores, the bean beetle attacks leguminous plants, especially beans. Both larva and adult feed on the undersides of leaves and sometimes on the pods. The adult is yellow, with black spots; the yellow, oval-bodied larva has forked spines. Bean beetles overwinter as adults and in early spring lay masses of 10 to 50 eggs on the undersides of leaves. One to four generations occur annually, each requiring about a month to mature. Since most damage occurs during July and August, early-maturing beans suffer the least damage. Removing old bean plants helps to destroy overwintering beetles, although many escape to nearby sheltered areas. Chemical insecticides are used for control. Before 1920 the bean beetle, also called Mexican bean beetle, was found only in the SW United States, but it now occurs throughout most of the United States, except on the Pacific coast. It is classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Coccinellidae.

May beetle: see June beetle.

June beetle or May beetle, a blackish or mahogany-colored beetle of the scarab beetle family, widely distributed in North America and especially abundant in the NE United States and the adjacent parts of Canada. It is also known as June bug, although true bugs belong to a different insect order. The adults, which may swarm in great numbers in early summer and are attracted to lights, feed by night on the foliage of deciduous trees and hide during the day. The eggs are laid in the soil, where the larvae, called white grubs, remain for two or three years, eating the roots and other underground parts of grasses, grains, and trees. The grubs cause great destruction to lawns and fir trees. Many birds and small mammals, such as skunks and pigs, root out the grubs and eat them. The insects pupate underground in the fall and emerge as adults the following spring. June beetles are sometimes called cockchafers, a name used primarily for some of their close relatives in the Old World. They are closely allied to the leaf chafers, including the rose chafer. June beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Scarabaeidae.

Japanese beetle, common name for a destructive beetle, Popillia japonica, of the scarab beetle family. Accidentally imported to the United States from Japan, it was first discovered in New Jersey in 1916 and is now widespread in the northeastern states, where it is a serious pest of lawns, orchards, and gardens. The adult is about 1/2 in. (13 mm) long with a metallic-green head and thorax and reddish-brown wing covers. Metamorphosis is complete (see insect). The eggs are laid in the ground; the small white larvae, called grubs, feed on the roots of grasses, sometimes killing them, and hibernate during the winter. Pupation occurs in the spring, and the adult emerges in midsummer, feeding on and destroying leaves, flowers, and fruits. Many methods of control have been tried, especially those involving the insect's natural enemies—e.g., parasitic wasps and flies, some of them imported from Japan; bacteria that cause the "milky disease" of grubs; and certain parasitic nematodes. None, however, have been entirely successful in controlling the spread of the beetle. Japanese beetles are classified in the phylum Arthropoda, class Insecta, order Coleoptera, family Scarabaeidae.

Colorado potato beetle: see potato beetle.

Any of some 2,000 species (family Cicindelidae) of voracious beetles, found worldwide but mostly in the tropics and subtropics. The larva waits at the top of its burrow (up to 2 ft, or 0.7 m, deep) and grasps approaching insect prey with sicklelike jaws. Hooks on the abdomen anchor it so that the struggling victim cannot pull away, and the prey is dragged into the burrow and eaten. The slender, long-legged adults, less than an inch (25 mm) long, have long jaws that can inflict a painful bite. Many are iridescent blue, green, orange, or scarlet.

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or snout beetle

Any of about 40,000 beetle species in the largest family of beetles, Curculionidae, which is also the largest family in the animal kingdom. Most weevils have long, elbowed antennae that may fold into special grooves on the prominent snout. Many species are wingless. Most species are less than 0.25 in. (6 mm) long, are plainly coloured and marked, and feed exclusively on plants. Some species are more than 3 in. (80 mm) long. The larvae may feed on only a certain part of a plant or a single plant species; adults are less specialized. The family includes many destructive pests, including the boll weevil.

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Small beetle (Anthonomus grandis) found almost everywhere cotton is cultivated. It is the most serious cotton pest in North America. Adults vary in size according to how much food they received as larvae, but they average about 0.25 in. (6 mm) long, including the long, curved snout. In the spring adults deposit eggs in cotton buds or fruit. After hatching, the larvae live within the cotton boll, destroying the seeds and surrounding fibres. Because the larvae and pupae remain inside the cotton bolls, they cannot be killed with insecticides. The boll weevil destroys an estimated three to five million bales of cotton annually.

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Any of about 30,000 beetle species (family Scarabaeidae), found worldwide, that are compact, heavy-bodied, and oval. Each antenna terminates in three flattened plates that fit together to form a club. The outer edges of the front legs may be toothed or scalloped. Species range from about 0.2 to 4.8 in. (5 to 120 mm) long and include one of the heaviest known insects. One species of dung beetle, Scarabaeus sacer, was sacred to the ancient Egyptians. Many species are agricultural pests (e.g., chafer, Japanese beetle, June beetle); many are popular with insect collectors because they are large and have beautifully coloured, hard, highly polished forewings.

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Destructive species (Lema trilineata) of leaf beetle (family Chrysomelidae). Less than 0.25 in. (6 mm) long, it is yellow and has three black stripes on its wing covers. Eggs are laid on the underside of a potato leaf, on which both larvae and adults feed. The larvae are camouflaged by excrement the beetles pile on their back. Two generations are produced each year; the second overwinters in the ground in the pupal stage. Seealso Colorado potato beetle.

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or ladybird beetle

Any of the approximately 5,000 widely distributed beetles of the family Coccinellidae. The name originated in the Middle Ages, when the beetle was dedicated to the Virgin Mary and called “beetle of Our Lady.” Ladybugs are hemispheric and are usually 0.3–0.4 in. (8–10 mm) long. They have short legs and are usually brightly coloured with black, yellow, or reddish markings. Several generations are produced each summer. Ladybugs are often used to control such insect pests as aphids, scales, and mites, which they eat. Several species of ladybugs feed on plants.

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Any member of about 700 species (family Dermestidae) of widely distributed beetles that are household pests. Usually brown or black, some are brightly coloured or patterned, and they vary in shape from elongated to oval. Dermestids range from 0.05 to 0.5 in. (1 to 12 mm) long and are covered with hairs or scales that easily flake off. The wormlike larvae feed on furs, skins, feathers, horn, and hair; some feed on cheese and dried meats or on carpets, rugs, furniture, and clothing. Two are museum pests that have destroyed collections of stuffed animals; museums and collectors must either have pestproof display shelves or continuously apply pesticides. The larvae of carrion-feeding species are sometimes used to clean the soft tissue attached to animal skeletons.

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Any member of the beetle subfamily Alticinae (family Chrysomelidae), found worldwide. It is tiny (less than 0.25 in. [6 mm] long) and dark or metallic in colour. The enlarged hind legs are adapted for jumping. Flea beetles are important pests of cultivated plants (e.g., grapes, cucumbers, melons, tobacco, potatoes, and tomatoes). The adults feed on the leaves, the larvae on the roots. Some flea beetles carry plant diseases (e.g., early potato blight).

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Any member of one subfamily (Scarabaeinae) of scarab beetles, which shapes manure into a ball (sometimes as large as an apple) with its scooperlike head and paddle-shaped antennae. They vary from 0.2 to more than 1 in. (5–30 mm) long. In early summer it buries itself and the ball and feeds on it. Later in the season the female deposits eggs in dung balls, on which the larvae will later feed. They are usually round with short wing covers (elytra) that expose the end of the abdomen. They can eat more than their own weight in 24 hours and are considered helpful because they hasten the conversion of manure to substances usable by other organisms.

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Borer insect (beetle species Xestobium refuvillosum) that tends to be small (less than 0.5 in., or 1–9 mm) and cylindrical. When disturbed, it usually pulls in its legs and plays dead. It makes a ticking or clicking sound by bumping its head or jaws against the sides of the tunnels it creates as it bores into old furniture and wood, a sound that, according to superstition, forecasts a death.

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Any of several leaf beetles (genus Diabrotica) that are important pests. They are greenish yellow, marked with black spots or stripes, and 0.1–0.5 in. (2.5–11 mm) long. The striped cucumber beetle and spotted cucumber beetle both feed on garden plants, and their larvae feed on the roots.

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Any of approximately 2,000 species of beetles (family Meloidae) that secrete an irritating substance, cantharidin, which is used medically as a topical skin irritant to remove warts. In the past, cantharidin was often used to induce blisters, a common remedy for many ailments, and the dried remains of Spanish fly (Lytta vesicatoria) were a major ingredient in so-called love potions. Adult blister beetles, which are often brightly coloured, range between 0.1 and 0.8 in. (3–20 mm) in length. Blister beetles are both helpful and harmful to humans; the larvae eat grasshopper eggs, but the adults destroy crops.

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Any member of the beetle family Scolytidae, many of which severely damage trees. Bark beetles are cylindrical, brown or black, and usually less than 0.25 in. (6 mm) long. A male and females (as many as 60 females with each male) bore into a tree and form a chamber where each female deposits her eggs. The emerging larvae bore away from the chamber, forming a characteristic series of tunnels. Different species attack particular trees, damaging roots, stems, seeds, or fruits. Some species transmit disease (e.g., elm bark beetles carry spores of the fungal Dutch elm disease).

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Large European beetle (Melolontha melolontha) that damages foliage, flowers, and fruit as an adult and plant roots as a larva. In Britain, the name refers more broadly to any of the beetles in this subfamily (Melolonthinae), which are known in North America as June beetles. Seealso chafer, scarab beetle.

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or May beetle or June bug

Any insect of the genus Phyllophaga, belonging to a widely distributed, plant-feeding scarab beetle subfamily (Melolonthinae). These red-brown beetles commonly appear in the Northern Hemisphere on warm spring evenings and are attracted to lights. Heavy-bodied, they are 0.5–1 in. (1.2–2.5 cm) long and have shiny wing covers. They feed on foliage and flowers at night, sometimes causing considerable damage. The larvae live in the soil, and can destroy crops and kill lawns and pastures by severing the grasses from their roots; they are considered excellent fish bait.

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Scarab beetle (Popillia japonica) that is a major pest of plants. Introduced accidentally from Japan into the U.S. in 1916, Japanese beetles are known to feed on more than 200 species of plant. Their larvae feed underground on roots; adults feed on flowers, fruit, and foliage. They range from Maine to South Carolina, and infestations have occurred in other parts of North America. The adult, about 0.4 in. (10 mm) long, is bright metallic green with coppery-brown wing covers. Control efforts include the use of poisonous sprays and a disease-inducing bacterium and introduction of the beetle's natural enemies (certain parasitic wasp and fly species).

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or potato bug

Leaf beetle (Leptinotarsa decemlineata, family Chrysomelidae) native to western North America. It began feeding on the leaves of cultivated potatoes when the plants were introduced into western North America, and by 1874 it had become an important and widespread pest. It has a hemispherical body, about 0.4 in. (10 mm) long, and is orange-red or yellow, with black stripes on the wing covers. Depending on climate, potato beetles may produce one to three generations each year.

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