Beetles

"Any foolish boy can stamp on a beetle, but all the professors in
​the world cannot make a beetle."
- Arthur Schopenhauer

Introduction

Beetles are insects in the order Coleoptera. They have a forward pair of wings that have evolved to be protective, hardened cases for their more delicate wings used for flight. Beetles can be found in almost every habitat except the ocean and the polar regions, and interact with their ecosystems in several important ways. They feed on plants and fungi, help to break down plant debris, and eat other invertebrates. Although they can be pests to some crops and landscape ornamentals, most species of beetles are considered to be beneficials in the landscape. ​The body of a beetle is divided into three parts. Their heads hold their eyes, mouths, brains, and antennae. There are some species of horned beetles that have extensions on their heads. Their thorax arranges their wings, legs, and thick, hardened elytra.
In desert species, beetles are able to trap moisture between their wings and bodies, helping them to survive when water is scarce. Alternatively, beetles that live underwater trap air under their elytra for later use. Their abdomens hold organs for digestion and reproduction.​

Beetle Behavior

Most beetles are active at night, though some are active during the daytime, especially if they have chemical defenses to use if threatened. They use their flexible antennae to find food, mates, and areas to lay eggs. They also alert other beetles to potential predators in their midst. Their compound eyes are sensitive to movement, as well. Most beetle species can fly, although clumsily. Their legs will typically reveal their main transportation method or other behaviors; long, slender legs of ground beetles are made for speed. Legs that are broad and ridged are used for digging, and are commonly seen in species of dung beetle. Curved, paddle-like legs are used for swimming in water beetle species. Many beetles can be seen basking in the sun in preparation for movement, as they need to warm up before attempting flight or fast ground speeds.
Many species of beetle can fly.
Beetles typically need to warm themselves in the sun before attempting to fly or run quickly.
The fastest beetles on earth can run about 5 miles per hour.
Beetles have evolved to be able to tap into most sources of sustenance available. They will consume almost anything, including other insects, carcasses, plants, pollen, and even poop. Predaceous beetles living in aquatic environments will catch and eat small fish and tadpoles. Some beetles use their sticky tongue similar to a frog, extending it to catch flying insects. There are even beetles that have tube-like mouthparts perfect for sucking up plant nectar. Beetles lay eggs, typically near areas that have an abundant food source. Some species of beetles provide parental care to their young, others do not. In the larval stage, which can last as long as several years, they will feed voraciously in order to gather up enough energy for their continued development. There are a varying number of instar stages, depending on the species, but eventually all beetles will develop hardened outer wings, strong legs, and various feeding and mating appendages by the time they are fully mature.

Beetle Species

There are around 400,000 described species of beetles, with new ones being discovered frequently. Coleopterists (scientists who study beetles) have estimated that the total species of beetles worldwide is between 0.9 and 2.1 million.
Acalymma vittatum
​(Striped Cucumber Beetle)
Serious pest of gourd and squash crops, yellow with black stripes. To 0.2 inches long, native to North America.
Acilius mediatus
(Predaceous Diving Beetle)
Native to North America, these beetles are found in creeks and ponds in spring and summer. Eats aquatic arthropods.
Alaus oculatus
(Black-and-White Click Beetle, Southwestern-Eyed Click Beetle)
To 1.8 inches long, with oval patches of scales framed in white, forming 'false eyes'. Central and North American species.
Anomala spp.
(Shining Leaf Chafer)
Feed on grass roots, becoming pests in invaded areas. Typically greenish-metallic and relatively small.
Anthrenus verbasci
(Varied Carpet Beetle)
To 0.12 inches long, with mottled black, brown and cream bodies. Household and museum pests that damage carpets, furniture, and clothing.
Anthonomus grandis
(Boll Weevil)
Feeds on cotton buds and flowers and native to central Mexico. Widespread in the U.S., devastated the cotton industry in the 1920's. Under 1/4 inch long.
Asbolus verrucosus 
(Blue Death-Feigning Beetle)
Omnivorous beetle adapted to desert life. Feign death when threatened and have a blue waxy coating to prevent moisture loss. To 0.83 inches long.
Attagenus unicolor
(Black Carpet Beetle)
To 0.2 inches long, can be a serious household pest. Feed on natural fibers. Begin life cream-colored, adults are dark brown to black.
Buprestidae spp.
​(Metallic Wood-Boring Beetle, Jewel Beetle)
Beetles in this family have speactacular colors, and range from 0.12 to 3.15 inches long. 
Calligrapha spp.
​(Calligrapha Beetle)
Used as biological pest control for invasive plants, some species are also considered pests themselves to sunflowers and other crops.
Camptosomata spp.
​(Case-Bearing Leaf Beetle)
Larvae carry around a casing of waste material for protection.
Cantharidae spp.
(Soldier Beetle, Leatherwing)
Feed on nectar, pollen, and smaller insects. Long-bodied in a range of colors.
Carabidae spp.
​(Woodland Ground Beetle)
Native to North America and Europe, shiny black or metallic beetles. Very fast beetles (5.6 mph in flight). Landscape beneficials.
Carabus nemoralis
​(European Ground Beetle)
Common in North America, these beneficial predators eat slugs
Carabus veltinghoffii
​(Veltinghoff's Ground Beetle)
Native to Europe, Northern Asia, and North America.
Cerambycidae spp.
​(Horse Bean Longhorn Beetle)
These beetles have very long antennae, and are found worldwide. Feed on plant tissue, can cause extensive damage to lumber and living trees.
Chalcophora angulicollis
​(Western Sculptured Pine Borer)
These metallic wood-boring beetles are found in western North America, and have a textured, shimmery shell.
Chalcophora virginiensis (Sculptured Pine Borer)
Endemic to forests in the US and Canada. Dark copper with lighter markings.
Charidotella sexpunctata
(Golden Tortoise Beetle)
Native to the Americas, reddish-brown with black spots to mirror-like gold. Changes color when disturbed. Consumes foliage of bindweed, morning glory, and sweet potato.
Chlaenius tricolor
​(Vivid Metallic Ground Beetle)
Native to an area that spans from southern Canada to Guatemala.
Chrysomela scripta
(Cottonwood Leaf Beetle)
Native to Central and North America.
Cleridae spp.
​(Checkered Beetle)
Worldwide distribution; To 0.94 inches long. Typically brightly colored with black markings.
Coccinella septempunctata
​(Seven-Spot Ladybird)
Red with black spots, these beetles feed on aphids and larvae. To 1/2 inch long.
Coleomegilla maculata
​(Spotted Pink Lady Beetle)
To 1/4 inch long, bright pink-red to orange with black spots and a flattened body. Feed on insect prey.
Creophilus maxillosus
​(Hairy Rove Beetle)
Shiny black beetles with some grey-cream mottling. To 0.98 inches long. Found in woods in spring to autumn. Feed mostly on maggots.
Cryptolaemus montrouzieri
​(Mealybug Destroyer Beetle)
Native to Australia, these beetles feed on mealybugs and scale insects, and is used in citrus orchards for this purpose.
Cucujus clavipes
​(Red Flat Bark Beetle)
Native to North America, to 1/2 inch long. Bright or dull red in color. Feeds on phloem of plants and small insects.
Curculio glandium
​(Acorn Weevil)
​With a long, protruding snout used for piercing. Deposits eggs in acorns, larvae consume the fruits. Can be significant pests of oak and other acorn-bearing trees.
Cylas formicarius
​(Sweet Potato Weevil)
Native to many areas around the world.
Cyphocleonus achates
(Knapweed Root Weevil)
Native to Europe and the Mediterranean, these dark grey white speckled beetles reach 0.6 inches long. Used to control knapweed.
Deloyala guttata
(Mottled Tortoise Beetle)
Native to the Americas, these beetles have shiny shield-like coverings.
Dermestes lardarius
​(Larder Beetle, Moisture Bug)
Found worldwide, eats processed animal products like cheese, pet food, skins and hides, and also eats grain. Black with tan and red markings.
Diabrotica undecimpunctata
​(Spotted Cucumber Beetle)
North American species that is a major agricultural pest of cucurbits, beans, cotton, and corn. Vectors of bacterial wilt and mosaic virus.
Eburia quadrigeminata
(Ivory Marked Beetle)
To 0.98 inches long, with tan bodies that have white markings. Larvae feed on old hardwood, including timber, that is in good condition.
Elateridae spp.
​(Click Beetle)
Most species are under 0.78 inches long, and are brown or black without markings. Larvae are called wireworms, which can be serious agricultural pests.
Eleodes dentipes
(Dentate Stink Beetle)
Desert stink beetle that reaches 1.1 inches long, common in rotting wood and dry leaves.
Enaphalodes rufulus
​(Red Oak Borer)
Epicauta pensylvanica
​(Black Blister Beetle)
A species of burning blister beetle.
Epilachna borealis
(Squash Beetle)
​Common pest of squash and gourd plants, with orange-red bodies that have black spots.
Erotylidae spp.
(Pleasing Fungus Beetle)
Feed on plant and fungal matter, some are pollinators, others are pests of significance. Most are inoffensive.
Euphoria kernii
​(Kern's Flower Scarab)
Galerita bicolor
(False Bombardier Beetle)
Native to the east and southern areas of the US. To 0.9 inches long, with black bodies and orange-red legs and thorax.
Glischrochilus quadrisignatus
​(Four-Spot Sap Beetle)
North American pest beetle that feed on fruits and vegetables that are rotting or overripe, leaving deep holes, similar to those made by slugs.
Gyrinidae spp.
​(Whirligig Beetle)
Surface swimmers that dive when threatened. Shiny black bodies to 0.7 inches long maximum.
Harmonia axyridis
​(Asian Lady Beetle, Harlequin)
Established worldwide, these beetles feed on aphids and scale insects. Red with black spots, to 1/3 inch long.
Hippodamia convergens
​(Convergent Lady Beetle)
Common in North America, these beetles eat aphids, and are red-orange with black spots.
Histeridae spp.
​(Hister Beetle, Clown Beetle)
​Diverse group of beetles useful for forensic investigations and controlling livestock pests. Black, sometimes with red markings.
Hopliini spp.
​(Monkey Beetle)
Important pollinators of plants with white, yellow, pink, orange, or blue flowers.
Hydrophilidae spp.
(Water Scavenger Beetle)
​Worldwide distribution, shiny black beetles that prefer moist environments like wetlands and ponds.
Hyperaspis signata
(Signate Lady Beetle)
Found in North America.
Lampyridae spp.
​(Lightning Bugs, Fireflies)
These bioluminescent beetles have brown, striped bodies and reddish heads, up to one inch long.
Lema daturaphila
​(Three-Lined Potato Beetle)
To 0.3 inches long, with yellow bodies, red heads and black stripes. Pests of Solanaceae and Physalis crops.
Leptinotarsa decemliniata
(Colorado Potato Beetle)
Major pest of potato crops, these beetles are yellow-orange with brown stripes, to 0.43 inches long.
Lilioceris lillii
(Scarlet Lily Beetle)
Consumes leaves, stems, buds and flowers of lilies, fritillaries and other Liliaceae members. Considered a pest.
Malachius aeneus
(Scarlet Malachite Beetle)
North American widespread beetle, frequent pests of cereal crops.
Meloe spp.
(Oil Beetle)
These beetles release bright orange oily droplets from joints. Metallic black bodies.
Meloidae spp.
​(Margined Blister Beetle)
​Known worldwide, these toxic beetles secrete substance that can cause blisters. Predators of bees and grasshopper eggs.
Melyridae spp.
(Soft-Winged Flower Beetles)
To 0.4 inches long, these beetles can be solid or patterned with colors of black, brown, yellow, or red. Predaceous beetles.
Monochamus galloprovincialis
(Pine Sawyer Beetle)
Strong fliers, these beetles have very long antennae, and are typically tan, mottled with lighter colors.
Monochamus scutellatus
(Beetles/White-Spotted Sawyer)
North American beetle with black bodies marked with cream. Common in post-fire forest landscapes. Bore into wood, degrading it aesthetically.
Nicrophorus spp.
​(Burying Beetle, Sexton Beetle)
Black with red or orange markings. Bury carcasses of small animals for their larvae to feed on.
Neoclytus acuminatus
(Red-Headed Ash Borer)
To 0.63 inches long, with reddish-brown bodies that have light yellow bands. Feed on sapwood of dead trees. Infests weak or newly planted trees, and can be a nursery pest.
Ocypus olens
​(Devil's Coach Horse)
Widespread species that can exude smelly substance. Typically black, to 1.25 inches long. Raises its abdomen like a scorpion when threatened. Can cause a painful bite.
Olla v-nigrum
​(Ashy Gray Lady Beetle)
Native to Central and North America as well as Oceania. Pale grey-tan with black spots. Prey on psyllids, aphids, stink bugs, and butterfly and beetle larvae.
Osmoderma eremicola
​(Hermit Flower Beetle)
Native to North America, with shiny, dark brown bodies to 1.25 inches long. Found in wooded areas, gives off a leathery odor.
Otiorhynchus ovatus
(Strawberry Root Weevil)
Pests of strawberry and other plants. Dark brown-black and 1/4 inch long. Cannot fly. These beetles are all female, and reproduce asexually.
Otiorhynchus sulcatus
​(Vine Weevil)
Common in North America and Europe, these small beetles are pests of many garden plants. They are dark brown to black, and cannot fly.
Phloeodes diabolicus
​(Diabolical Iron Clad Beetle)
Native to California and Baja California, Mexico, these beetles feed on fungi under rotting tree bark. Very durable beetle.
Phyllophaga spp.
​(May Beetle, June Bug)
Ranging from 0.5 to 1.4 inches long, with orange-red or black-brown bodies. Feed on foliage of trees and shrubs, causing significant damage in large numbers.
Polyphylla decemlineata 
(Ten-Lined June Beetle)
Found in the western U.S. and Canada, this species can hiss when disturbed. Larvae are agricultural pests. To 1.5 inches long, with white stripes on their brown bodies.
Polyphylla variolosa
​(Variegated June Beetle)
Reddish-brown beetles native to North America.
Popillia japonica
(Japanese Beetle)
Native to Japan, widespread in Europe and North America, where they are considered pests of many different plants, including Roses, Canna, Grapes, Birch, and Crape Myrtle.
Prionus californicus
(California Root Borer Beetle)
These western American native beetles are pests of orchard and vine crops like hops and grapes. Reddish-brown bodies, emerging in June to early August.
Psephenidae spp.
(Water Penny Beetle)
These aquatic beetles are signal species for healthy water ecosystems. Round beetles that are typically dark brown. Larvae look a bit like scale insects.
Pyrochroidae spp.
​(Fire-Colored Beetle)
Worldwide distribution, these beetles feed on fungus under bark of dead trees. Typically black and bright red-orange.​
Ripiphoridae spp.
​(Wedge-Shaped Beetle)
Predators and parasites of wasps, bees, cockroaches, and beetles. 
Rosalia funebris
​(Banded Alder Borer)
Long antennae on dark-colored beetles that have white banding. To 1.5 inches long. Attracted to recently painted buildings. Larvae consume wood, adults consume flowers. Not considered a pest.
Rutpela maculata
(Spotted Longhorn)
Worldwide distribution, to 0.8 inches long with yellow bodies that are often marked with black and red. 
Sandalus niger
(Cedar Beetle)
Found in North America, these brown beetles have black heads and feathery red antennae. Lay their eggs in the bark of Elm trees.
Saperda calcarata
​(Poplar Borer)
Native to Canada and the United States.
Scarabaeoidea spp.
(Hercules Beetle, Goliath Beetle)
A superfamily containing some of the largest beetles on the planet. Typically brown to black in color, and can fly.
Scaphinotus spp.
(Narrow-Collared Snail-Eating Beetle)
Native to North America, this species eats snails and is commonly found in areas where snails are present. Flightless.
Scarites subterraneus
(Big-Headed Ground Beetle)
Found in the Caribbean, Central America, and North America. Between 0.6 and 1.2 inches long. Typically black with large jaws used to hunt invertebrates.
Scirtidae spp.
​(Marsh Beetle)
​Consume decomposing plant materials near bodies of water, larvae can be found in flowing water. Small and brown.
Sitophilus oryzae
​(Rice Weevil)
​Pest of maize, wheat and rice storage, to 0.2 inches long. Typically reddish-brown with long snouts.
Sitophilus zeamais 
(Maize Weevil)
A major pest of stored cereal crops and fruits, with dark brown bodies to 0.2 inches long.
Sphenophorus aequalis
(Clay-Colored Billbug Beetle)
Native to North America.
Staphylinidae spp.
(Rove Beetle)
From 0.04 inches to 1.4 inches long, these thin beetles look almost like earwigs, and can be anywhere from reddish-brown to iridescent blue-green.
Stegobium paniceum
​(Drugstore Beetle, Bread Beetle)
Infests a wide variety of dry plant products, including cereals. To 1/8 inch long, with red-brown bodies.
Stenolophus lecontei
​(Leconte's Seedcorn Beetle)
​Native to North America.
Synaphaeta guexi
​(Spotted Tree Borer Beetle)
Native from British Colombia down to California.
Tegrodera aloga
(Iron Cross Blister Beetle)
From Arizona, California, and Sonora, Mexico, has a black cross on its wings, which are typically bright yellow. Found in groups. Feed on alfalfa and other desert plants, and can drink nectar.
Tenebrionidae spp.
​(Darkling Beetle)
These beetles inhabit dark places, and are active by day. Typically black, sometimes with yellow-orange markings.
Tetracha carolina
​(Carolina Tiger Beetle)
Trichiotinus piger
​(Bee-Like Flower Scaber)
Consume leaves and flowers of various tree and plant species, but rarely cause serious damage. Grubs are occasional pests in agricultural fields and vegetable gardens.
Trichocnemis spiculatus
​(Ponderous Borer Beetle)
Native to western North America, these beetles are brown with black heads and legs, and lay eggs in the bark of dead and dying Pines.
Trichodes ornatus
(Ornate Checkered Beetle)
These beetles live in bee nests, feeding on larvae or pollen. Adults feed on milkweed, yarrow, and yellow-flowered plants. To 0.6 inches long with black bodies striped with yellow or red.
Typocerus spp.

Beetles in the Garden

Overall, beetles are considered to be beneficial insects in landscapes. They create usable soil for vegetation by consuming and processing waste, rotten wood, other debris, and carcasses of other insects and animals. They act as pollinators, flitting from flower to flower and drinking their sweet nectar, similar to bees and butterflies. Their voracious appetite makes them perfect pest control, keeping their populations at manageable levels. Although they do so many good things in the landscape, they can also engage in some behaviors that do not endear them to gardeners or homeowners. There are a few notable groups of beetles to pay attention to when managing a garden ecosystem, including fruit, flower and bud beetles, leaf, stem, and seedling beetles, root beetles, and tree-boring beetles. These beetles, in either their adult or larval form, feed on plant parts, leading to crop loss, spread of disease in the garden, and lowered photosynthetic potential of landscape or vegetable garden plants.
For more information on creating a comprehensive, sustainable pest management system in your garden, consult the following page:

Videos

Learn all about beetles that can swim.

Resources and References

Wikipedia: Beetle