Beetles

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Volume 5 (Number 2) Summer 1996

This WAYNE'S WORD Is Dedicated To
The Amazing Insects Known As Beetles

[No, not the two-legged musical variety from England, but the six-legged type with
a chitinous exoskeleton and a pair of leathery elytra covering their flight wings
].


  1. Are Rhinoceros & Hercules Beetles A Threat To Bikers?
  2. Do Lightning Beetles Cause Forest Fires?
  3. Is Spanish Fly Really A Fly From Spain?
  4. Can Short Circuit Beetles Cause Blackouts?
  5. Can Sunscreen Lotions Protect You From Blister Beetles?
  6. Is It Politically Correct To Call Ladybird Beetles Ladybugs?     
  7. Do Dung Beetles Enjoy Rolling In Manure All Day?
  8. Do Extraterrestrials Read WAYNE'S WORD?


An assortment of beetles.

One Fifth Of All The 1.5 Million Living Species On Earth Are Beetles!

This is probably a more accurate representation of the number of described species of beetles compared with other animals, plants, algae and fungi. There are at least 350,000 described species. Considering all the undescribed species, the number may exceed 400,000!

  University of California Museum of Paleontology Evolution 101: Why So Many Beetles?  

There are more than 800,000 species of insects on earth, more than all the other plants and animals combined. Of this great number of insects, nearly half are beetles. Unlike other insects, beetles have a pair of leathery protective wings called elytra that cover their membranous flight wings. During flight, the elytra are spread apart and the two flight wings are unfolded and extended. Beetles come in a variety of shapes and colors, from red "ladybugs" and metallic green fig beetles to lightning beetles that glow in the dark and huge horned beetles resembling a miniature rhinoceros. Colorful beetles are used for jewelry and pins, and shiny tropical scarab beetles are strung together to make unusual necklaces. Beetles range in size from less than a millimeter (1/100 of an inch) to tropical giants over six inches long. The largest giants may weigh 40 million times more than their lilliputian relatives.

The world's largest beetle: Titanus giganteus, a member of the Cerambycidae native to South America. These large beetles can measure up to 170 mm (over 6 inches in length). Although the larvae are wood borers, the adults can inflict a painful bite. An adult male apparently bit and shattered a plastic ruler used as a size relationship by a photographer. One can only imagine what the powerful mandibles could do to your fingernail (or your finger). The giant beetle is compared with a minute flower beetle enclosed in a red circle. The flower beetle is only 4 mm in length (about 1/6th of an inch), smaller than the "foot" of Titanus giganteus. Other size relationships in this photo include the "head" of an ordinary straight pin, the "eye" of a sewing needle, and a millimeter ruler.

Size Relationships Used In Wayne's Word

One of the most amazing is the Hercules beetle (Dynastes hercules), native to the rain forests of Central America. This spectacular beetle has two enormous curved horns and looks like a creature from the age of dinosaurs. In fact, it is truly amazing that this monster can actually fly. For many years, a bronze sculpture of this remarkable beetle stood at the entrance to the San Diego Museum of Natural History in Balboa Park. If all the different species of plants and animals on earth were randomly lined up, every fifth one would be a beetle. Beetles have taken seriously the injunction "Be fruitful and multiply and replenish the earth."

Dynastes hercules, a spectacular hercules beetle from Costa Rica.

Male southwestern hercules beetle (Dynastes granti)
on display at the Red Rock State Park Visitor Center.

Dynastes granti, a female southwestern hercules beetle from Arizona.


Stag Beetle Family (Lucanidae)

Cottonwood stag beetle (Lucanus mazama).


The earliest known prehistoric beetles date back about 230 million years ago, a time when dinosaurs roamed the earth. With the advent of flowering plants about 65 million years ago, speciation in beetles occurred at an astronomical rate as they began to exploit the rapidly evolving angiosperms. Hard bodies of beetles preserve very well, and fossil records of beetles are found throughout the evolution of flowering plants. One of the most interesting locations for beetle fossils is the La Brea formation at Mckittrick, California where numerous Pleistocene animals became entomed in tar pits over 10 million years ago. The tar pits were formed as crude oil seeped to the surface through fissures in the earth's crust. Evaporation of the oils resulted in a thick, sticky substance resembling asphalt. Some of the beetles embedded in these formations are perfectly preserved in every detail.

This beetle became trapped in a tar pit nearly 11 million years ago, at a time when large glaciers dominated the landscape in North America. The elytra (wing covers) of this beetle are perfectly preserved. The beetle appears to be a streamlined water beetle, possibly belonging to the family Dytiscidae.

A modern-day water beetle in the family Hydrophilidae. This is probably the giant black water beetle (Hydrophilus triangularis). Water beetles are descendants of terrestrial insects and have evolved a number of adaptations for living in water. The bodies are streamlined to reduce drag as they swim. The flattened short legs are fringed with hairs and serve to propel the beetle through water. While submersed these beetles obtain oxygen from a bubble of air stored under their inner wings (elytra) and along the ventral surface of their thorax.

A swimming sunburst diving beetle (Thermonectus marmoratus) of the family Dytiscidae.

Volumes have been written about the amazing world of beetles. Adult short circuit beetles (Scobicia declivis) bore into lead sheathing of telephone cables causing short circuiting when moisture enters the small holes. Trunks of native California fan palms in the southwestern U.S. often contain large circular tunnels, the work of huge boring larvae (Dinapate wrightii), a member of the family Bostrichidae. The hardwood floor beneath a palm trunk section at the San Diego Museum of Natural History was deeply grooved by one of these larvae. The adult beetle is truly bizarre. In the late 1800's museums paid up to $1,000 to an enterprising collector for one of these striking beetles. The collector (probably a business major) reportedly inflated the value of his merchandise by keeping their exact location a secret.

The larva and adult of the palm-boring beetle (Dinapate wrightii).

See Palm Wood Bored By Larva Of Dinapate wrighii

Stout's hardwood borer (Polycaon stouti), another member of the family Bostrichidae. This beetle has very destructive larvae, particularly if you have wood construction in your home made of oak and maple. The larvae of this beetle can even bore into furniture!


Bombardier beetles (Brachinus spp.) inject an explosive mixture of hydroquinone, hydrogen peroxide plus several potent catalysts into a reaction chamber in the abdomen. Catalase breaks down the hydrogen peroxide into water and oxygen gas. Peroxidase oxidizes hydroquinone into benzoquinone. The mixture of chemicals and enzymes volatilizes instantly upon contact with the air, generating a puff of "smoke"" and an audible popping sound. This caustic flatulence is totally controlled by the beetle, otherwise it might accidentally blow up its rear end. The explosive discharge apparently discourages predators, either by chemical irritation, heat or repugnance. The temperature of the explosive mixture of gasses and fluids is over 100 degrees Celsius, the boiling point of water. This astonishing chemical defense mechanism is discussed by D.J. Aneshansley and T. Eisner (1969) in Science Vol. 165: 61-63.

Bombardier beetles of the genus Brachinus, a member of the large ground beetle family (Carabidae). These small beetles are about 13 mm long (1/2 inch). They are fairly common in southern California, particularly near streams, lakes and marshy areas. The wing covers (elytra) are dark blue-brown with a contrasting reddish-orange head and prothorax.


The body fluids of some blister beetles of the family Meloidae contain cantharidin, a substance that causes severe irritation and blistering of skin. This chemical is very sensitive to mucous membranes and is the active ingredient of "Spanish-fly," made from the ground up bodies of a European blister beetle (Lytta vesicatoria) . Although it has been used as a counterirritant, its use as an aphrodisiac is very unwise unless you are raising livestock or chickens.

Soldier blister beetles of the genus (Tegrodera).

A desert blister beetle (Lytta magister) on rabbitbrush (Chrysothamnus nauseosus).

The inflated blister beetle (Cysteodemus armatus), a curious beetle with a small head and inflated abdomen. Because it superficially resembles a spider it is sometimes called the desert spider beetle. This beetle feeds on ephemeral wildflowers as it scurries across sandy riverbeds and washes. The pitted back has several color variations.

Inflated Blister Beetles In Anza-Borrego Desert
See Desrt Blister Beetle In Anza-Borrego Desert
See An Amazing Bombardier Beetle (Brachinus sp.)


A metallic green fig beetle (Cotinus texana), so named because it is often found feeding on fig fruits during the warm summer months in southern California. It is also fond of other ripe, juicy fruits, such as peaches and plums. These attractive beetles spend their juvenile larval stage in the ground, often beneath manure piles, compost and haystacks.

A metallic green fig beetle (Cotinus texana) gorging itself inside a fleshy, ripe syconium of the Calimyrna fig (Ficus carica). Although masses of minute, aggressive Argentine ants (Iridomyrmex humilis) are also foraging in the syconium, the beetle is protected by a tough, impervious exoskeleton.

See: Beware Of The Argentine Ants


The pine sawyer is one of the largest beetles in urbanized areas of southern California. It belongs to the long-horned beetle family (Cerambycidae) The large, pale larva, up to 2 1/2 inches (6.3 cm) long, feeds on the wood of fallen logs and old conifer stumps. The adult beetle in above photo is over 3 inches long (including the extended antennae). It has a pair of powerful jaws (mandibles) that are capable of inflicting a painful pinch. At least they can leave an imprint on a piece of cardboard! The adults emerge from subterranean stumps in early summer. They are nocturnal and are attracted to lights. It is always a surprise when one of these big beetles lands on your window screen.

An adult pine sawyer beetle (Ergates spiculatus).
[Thanks to Jim Hogue at CSUN for the correct ID of this species.]

Another long-horned wood-boring beetle (Prionus californicus). The
antennal segments of the male (in this photo) are conspicuously lobed.

California prionus (Prionus californicus).  The large larva feeds on roots of
deciduous trees. It is similar to the pine sawyer beetle (Ergates spiculatus).

Phoracantha recurva, a long-horned wood-boring beetle introduced into southern California from Australia. According to A. V. Evans and J. N. Hogue (Field Guide to Beetles of California, 2006), it was first discovered at the University of California at Riverside in 1995. Another closely related species (P. semipunctata) was found in 1984 on dying eucalyptus trees in Orange County. The larvae of both species tunnel between the bark and wood, but construct their pupal chambers in the heartwood. Adult beetles are attracted to fallen branches and injured or water-stressed trees.

More Images Of Eucalyptus Wood-Boring Beetle


More long-horned wood boring beetles in the Rocky Mountains

A sawyer beetle (Monochamus sp.?) on a blue spruce (Picea pungens).

A friendly sawyer beetle on a coffee table in Wyoming.

See Close-Up View Of A Bark Beetle (Family: Scolytidae)


Another large beetle attracted to lights during summer nights in southern California is the ten-lined june beetle. It belongs to the large scarab beetle family (Scarabaeidae). This striking beetle has conspicuous white stripes on its wing covers (elytra). When taking off, the elytra move forward and a pair of larger, membranous flight wings unfold. The beetle makes an unusual squeaking sound when it is handled. Adult beetles feed at night on needles of coniferous trees.

An adult ten-lined june beetle (Polyphylla decemlineata).


Eupatorius gracilicornis, a large scarab beetle from Malaysia.

A male goliath beetle (Goliathus orientalis), a large scarab beetle from Africa.

A male stag beetle (Odontolabis castelnaudi), a large scarab beetle from southeast Acia.

Rhinoceras beetle Megasoma elephas, a large carab beetle from Costa Rica.


Several species of large scarab beetles (family Scarabaeidae) appear with the first soaking rain during late fall in coastal San Diego County and adjacent Baja California. They belong to the genus Pleocoma and are commonly referred to as rain beetles. The name Pleocoma is derived from two Greek roots, "pleos" (full or abundant) and "kome" (hair). The name translates into "very hairy," which describes these beetles perfectly, particularly their underside. Rain beetles are typically found in coastal foothills and canyons of chaparral and coastal sage scrub. After a soaking rain (usually one or more inches), male beetles make a sudden appearance at dusk, early morning, or on cloudy, drizzly days. The males fly in slow sweeping arcs throughout the foothills, keeping close to the ground in search of the larger, flightless females. They are attracted by a pheromone (chemical sexual attractant) emitted by the female as she waits at the surface of her subterranean burrow. The males are also attracted to lights and often bump into windows of houses in foothill areas. Since adult beetles do not feed, the male only has an energy reserve for a flight of a few hours before he literally runs out of "gas."

Male black rain beetle (Pleocoma puncticollis), a large scarab beetle that appears with the first soaking rain in San Diego County. The flattened, bilobed extension of the head (clypeus) is used for scooping soil as he pushes through the ground. The underside of the body is covered with dense black hair.

The larger, more rotund, flightless female rain beetle rarely leaves her burrow in the ground. She emits a pheromone that is apparently irresistible to the male, as she waits for him at the surface of her burrow. After mating, the female closes the entrance and lays eggs at the base of her burrow. Like the male, she is equipped with a rigid digging device at the end of her head called a clypeus. Both sexes of Pleocoma lack functional mouthparts and digestive tracts, and consquently do not feed during their brief adult life. With her powerful legs and clypeus, the female pushes and scoops the soil like a miniature bulldozer. Her eggs do not mature until the following spring or early summer.

A female rain beetle (Pleocoma sp.). She is larger than the male and spends most of her life below ground in her burrow. Like the male, she has a very hairy underside and is equipped with powerful legs and a sturdy clypeus on the front of her head.

Rain beetle larvae hatch from eggs deep in their mother's subterranean burrow. They are slow to develop, and have a life cycle lasting ten years or more. They feed on roots, fungal hyphae and other organic debris, eventually metamorphosing into adults. Adult males may wait a month or more before the first rains bring them into the open air for their mating flight. During this time, the females dig to the surface and wait for the males to arrive. Neither male nor female rain beetles feed as adults, their short adult life provides the vital transfer of genes and perpetuation of these remarkable species of beetles.

Male rain beetles (Pleocoma puncticollis) photographed in San Diego County.

Taxonomy, Biology & Distribution Of The Genus Pleocoma


Some beetles exhibit some rather peculiar behavior. Tumbling flower beetles (Mordella marginata) inhabit flowers and make some rapid tumbling movements to avoid capture. You would probably do some acrobatics too if you had a large spider after you. Dung beetles (Canthon laevis) spend much of their time rolling around a large ball of dung. Actually, this is very much like some of our jobs. Large, ground-dwelling beetles of the genus Eleodes (family Tenebrionidae) are commonly found wandering in the coastal mountains and deserts of southern California. When disturbed or threatened they exhibit the unusual behavior of raising their abdomen into the air. This "headstanding" alarm posture has earned them the name of "acrobat beetle."

Dung beetles at the elephant exhibit at the San Diego Zoo.

A carrion beetle of the family Silphidae, also known as the black burying beetle (Nicrophorus nigrita). According to James N. Hogue (Introduction to California Beetles, 2004), Nicrophorus demonstrates the most advanced behavior of parental care known in beetles. These beetles bury small animal carcasses to reduce competion with flies, ants and other carrion-feeding insects. This insures food for the beetles and their larvae. In addition, they use their sensitive red antennae to detect hydrogen sulfide and cyclic carbon compounds that are released from decaying carcasses.


Darkling beetles of the genus (Eleodes) have fused wing covers (elytra) and cannot fly. They are sometimes called "stink beetles" because some species apparently emit an odor when handled; however, I have never observed any disagreeable odor in the docile species shown in the above images.

Eloedes With An Odor

An Eloedes beetle in its characteristic "headstanding" alarm posture. Unlike most of the Eloedes beetles I have observed, this one definitely released a slightly disagreeable odor.

Ironclad Beetles (Phloeodes pustulosis), another member of the diverse family Tenebrionidae. These ground-dwelling beetles have fused wing covers (elytra) and cannot fly. They are fairly common in southern California. The common name is derived from their very hard body wall that can resist a sharp insect pin. When disturbed or threatened they retract their legs and antennae and remain motionless. They are thought to feed on decaying, fungus-ridden wood.

Apsena sp. in the family Tenebrionidae, subfamily Tenebrioninae, Tribe Eulabini. Found at the summit of Owens Peak northeast of Palomar College, San Marcos, CA.


This is not a large ant. It is a rove beetle, sometimes called the Devil's coach horse (Staphylinus olens). These large, ground-dwelling beetles belong to the family Staphylinidae and are occasionally found in urbanized areas of coastal southern California during September and October. This beetle has short wing covers (elytra) and does not fly. When alarmed it exhibits a threat posture by opening its formidable mandibles and raising the tip of its abdomen (right image). Although the abdomen has no stinging device, this display serves to ward off enemies. The alarm posture is well deserved because this beetle can inflict a painful bite into your finger. Two glands at the tip of the abdomen emit a malodorous yellowish liquid. Both adults and larvae are voracious predators. According to C.L. Hogue (1974 & 1993), Insects of The Los Angeles Basin, this beetle feeds on garden snails and slugs. Although it was originally introduced from Europe around or before 1931, it is probably beneficial in your garden.


Common calosoma (Calosoma semilaeve), a large beetle that runs free during daytime hours in search of prey. When disturbed or threatened it emits a foul oder that smells like burning electrical insulation.

See Another Long-Legged Calosoma Beetle

Larva of a ground beetle (Carabidae) from Anza-Borrego Desert.

Ground beetle and larva of the genus Calosoma in the family Carabidae. This predaceous genus is often called "caterpillar hunter." During April of 2005, the carabid larvae were very abundant in Anza-Borrego Desert feeding on the pupae (chrysalises) of the painted lady butterfly (Vanessa cardui). Note: In moths and butterflies that do not spin cocoons, the hard-shelled pupa is called a chrysalis.

See Painted Lady Butterfly

Laemostenus complanatus, a fast-running, predatory carabid beetle. Although native to northern Africa, this beetle is fairly common in southern California. It has been introduced around the world, including the Mediterranean region, western North America, southern South America, and parts of Australia and Tasmania.


There are some animal species with only females in the population. One of these is Fuller's rose weevil (Naupactus cervinus = N. godmanni = Asynonychus godmanni), a small flightless weevil introduced into California in the late 1800s. This beetle feeds on many cultivated plants and is especially troublesome in citrus groves where the adults eat new growth on young trees. The larvae feed on roots and make furrows in the bark. Eggs are laid on citrus fruits under the green calyx, and are transmitted during the shipment of infected fruits. Males have never been found in this species, so the females must produce viable eggs without fertilization, a phenomenon known as parthenogenesis.

Fuller's rose weevil (Naupactus cervinus), a small beetle introduced into southern California from South America. No males have been found in this species. The females produce viable eggs without fertilization, a phenomenon known as parthenogenesis. Weevils (snout beetles) belong to the large family Curculionidae.

The bamboo shoot weevil (Cyrtotrachelus longimanus), a large snout beetle native to southeast Asia.

Blue milkweed beetle (Chrysochus cobaltinus), a beautiful beetle that commonly feeds on milkweeds (Asclepias). It belongs to the large family Chrysomelidae. Photo taken in the northern Coast Range of California.

The glorious beetle (Plusiotis gloriosa), one of the most beautiful beetles in North America. It belongs to the large and very diverse family Scarabaeidae, along with June beetles, rain beetles and rhinoceros beetles. Adults feed on juniper foliage in the southwestern United States (Texas to Arizona and northern Mexico). Their striking color actually serves as camouflage by blending in with the native vegetation.

Glorious beetle (Plusiotis gloriosa) on display at the Red Rock State Park Visitor Center, Arizona.


The Chrysomelidae is a large family of leaf-eating beetles. Although some chrysomelids can cause serious damage to plants, there is one species that truly appears like a glistening golden droplet in your garden. This stunning, metallic gold beetle is slightly smaller than a ladybird beetle. It is called the golden tortoise beetle (Metriona bicolor). The sides of the thorax and elytra are flared out and extend beyond the body, thus hiding the head and much of the legs. This extended covering is the derivation of the name "tortoise beetle" or "turtle beetle." Although collected in Escondido (San Diego County), the golden tortoise beetle is relatively uncommon in southern California. It is more common in the eastern United States. Both adults and larvae feed on the leaves of morning-glories (Convolvulaceae) and related plants. In the case of the aggressive, fast-spreading bindweed (Convolvulus arvensis), this little beetle could actually be beneficial. In order to capture their beautiful golden luster, these beetles should be photographed alive. The color appears especially brilliant during mating season. On dead beetles the golden luster fades rapidly.

Golden tortoise beetle on bindweed leaf (Convolvulus arvensis).

Golden tortoise beetle (Metriona bicolor). Note the outer extension of thorax and elytra.

A deceased golden tortoise beetle (Metriona bicolor).

References:

  1. Borror, D.J. and D.M. DeLong. 1964. An Inroduction To The Study of Insects. Holt, Reinhart and Winston, New York.

  2. Evans, A.V. and J.N. Hogue. 2006. Field Guide to Beetles of California. University of California Press, Berkeley, California.

  3. Evans, A.V. and J.N. Hogue. 2004. Introduction to California Beetles. University of California Press, Berkeley, California.

  4. Hogue, C.L. 1993. Insects of the Los Angeles Basin. Natural History Museum of Los Angeles County.

Satirical Suggestions On How To Live
Safely In A World Filled With Beetles:

  1. Always wear a helmet and face mask while riding a motorcycle through regions with rhinoceros beetles. This is especially true at night because these flying "rhinos" are attracted to the headlights.

  2. Do not attach strings to the legs of large beetles to control their flight. This is not only cruel, but some beetles can bite.

  3. Do not place Spanish fly powder in the food or drink of a potential mating partner, not even if they say it is O.K.

  4. Buy a lovely beetle body necklace and wear it to an elegant social engagement.

  5. Stock your swimming pool with large, predaceous diving beetles and allow them to remove insect pests and unwanted guests.

  6. Do not place palm trunks on your hardwood floors, they might contain the huge larvae of palm-boring beetles.

  7. Do not insult beetles by referring to them as "flies," "pigs" or "bugs."

  8. If you are fed up with your present job, try rolling around a large, compact ball of steer manure all day long.


The WAYNE'S WORD Official
Beetle Bonus Bonanza:

   View The Official Wayne's Word Fun With Beetles Page.

   View A June Beetle In Flight. The two leathery elytra are spread
apart to reveal the unfolded, membranous fight wings.

   View A Genuine Beetle Body Necklace.

   View An Enormous Hercules Beetle From Costa Rica.

   View A Pizza Graph Showing The Percentage Of Beetle Species
Compared With All The Species Of Plants And Animals On Earth.

   Try Your Luck At Finding All The Beetles In A Beetle Word Puzzle.

   Answers To The Beetle Word Puzzle.

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