Beetles Examples


Anobiid beetle

Text and pictures of these examples by Don McIntire

Anobiid beetle (Trichodesma cristata)

Adult: 5-6 mm

Order Coleoptera/ Family Anobiidae – Death-watch beetles

The larvae of Trichodesma spp. feed in dry dead wood and have also been found to invade houses and other structures, in some cases, causing considerable damage to timbers. This species was intercepted in pheremone traps set out to catch bark beetles at the reserve. Many of the Anobiid species of North America are what is termed glabrous, having little or no body hair, but this remarkable little species is very hairy, or a pubescent beetle as you can see. Intermixed with the light hairs are patches or tufts of stiffer black hairs making the genus, Trichodesma, easily recognized. Death-watch beetles get their name from the fact that they, like so many other borers, make a ticking noise in infested wood. The early Europeans gave them this name because when the sound was heard in the quiet of hospitals or the bedsides of the dying.


Arboreal click beetle

Arboreal click beetle (Euthysanius spp.)

Adult: 20 mm

Order Coleoptera/ Family Elateridae/ Subfamily Oestodinae

Euthysanius is common to the Reserve as evidenced from those caught in pheromone traps in summer to fall months of 2001, but nothing seems to be known of their habits except that they are subcortical, being found under the bark of various Pinus spp. Whether the larvae are predators of other bark insects or feed in rotting wood, is yet to be discovered. The pectinate, or branched antennae is diagnostic of this elaterid species, though they are also a feature of the closely related False Click Beetles, the Eucnemidae, which are also found to be subcortical in habit.


Ground Beetle

Big-headed Ground Beetle (Scarites subterraneus)

Adult: 15-20 mm

Order Coleoptera/ Family Carabidae/ Tribe Scaratini – Pedunculate Ground Beetles

This is a common and widely distributed predaceous ground beetle that is often found in shallow, cup-like burrows under objects such as stones, boards and logs in yards, fields in wet areas of San Diego County. It inhabits the lowland parts of the Reserve where there are mostly willows, like the Arroyo willow, Salix lasiolepus, and Black willow, S. goodingii, along the trail leading south into Sorrento Valley. Scarites is considered beneficial for destroying cutworms and other pests which destroy bedding plants and crops. The beetle, when disturbed, has an interesting defense of stiffening its legs and body to appear dead.


Black Rain

Black Rain Beetle (Pleocoma puncticollis)

Adult: Male: 30-35 mm; Female: 45 mm

Order Coleoptera/ Family Scarabaeidae/ Subfamily Pleocominae – Rain Beetles

A resident species of Torrey Pines State Reserve and generally distributed throughout the coastal North County. The male Black Rain Beetle has a patent leather look to it with dense black hair ventrally. The females, not pictured, are dark chestnut brown and considerably larger than their mates, with a high, ball-like appearance and venter with yellowish hair. With the first fall and or winter rains the flightless female, which stays in her burrow, wafts the air with her irresistible scent and awaits the arrival of the males. With powerful legs and a scoop-like clypeus, the front edge of the head, she can excavate an elaborate tunnel in even fairly compacted soil. As adults the rain beetles do not apparently feed and are probably short-lived. The larvae feed on the roots various shrubs and conifers, taking eight to twelve years to reach maturity (from Western Forest Insects, Furniss and Carolin, 1980).


California Prionus

California Prionus (Prionus californicus)

Adult: 40-60 mm

Order Coleoptera/ Family Cerambycidae – Long-horned Beetles

The giant root borer, as it is sometimes called, is distributed over much of the state where it feeds on a great variety of woody plant roots and stumps in the larval stage, including the Torrey Pine. The whitish larvae, when fully grown and ready to pupate, attain the length and girth of a man’s middle finger. Development from larva to adult may take from two to five years.


Caterpillar Hunter

Caterpillar Hunter (Calosoma cancellatum)

Adult: 20 mm

Order Coleoptera / Family Carabidae – Predaceous Ground Beetles

Distributed in the sandy riparian and salt marshes of coastal areas and Imperial Valley. Among the caterpillar hunters of other parts of the U.S. there are some very colorful and iridescent species like the Firey Searcher, Calosoma scrutator, but those found in Southern California are mostly black. The strial punctures of the elytra of C. cancellatum are metallic green. Calosoma semilaeve, which is all black, is often seen climbing plants in search of caterpillars, but C. cancellatum apparently stays on the ground to hunt cutworms. The large larvae of the caterpillar hunters are heavily armored and conceal themselves in leaf litter under plants during the day and feed as the adults.


Checkered beetle

Checkered beetle (Enoclerus spp.)

Adult: 6-8 mm

Order Coleoptera/ Family Cleridae – Checkered beetles

These beetles are considered beneficial predators. The spindle-shaped larvae with dark head and thorax are found in the galleries of bark beetles where they feed on eggs, larvae and adults. Adults of Enoclerus also prey on adults of bark beetles but are at times found on flowers of such plants as Flat-topped buckwheat, Eriogonum fasciculatum, and Southern blue elderberry, Sambucus mexicanum. There are many species of Enoclerus and new species are brought to light in the scientific community as more study is made of our forests.


Darkling beetle

Darkling Beetle (Apsena pubescens)

Adult: 5-6 mm

Order Coleoptera/ Family Tenebrionidae – Darkling Beetles.

Common in coastal sagescrub and chaparral communities. The adults feed on plant detritus and are often found in debris beneath California buckwheat, Eriogonum fasciculatum.



Flatheaded Borer (Buprestis laeviventris)

Adult: 17 mm; Larva: to 25 mm

Order Coleoptera/ Family Buprestidae – Metallic wood-boring beetles

The beautiful buprestid beetles are often called flatheaded borers by foresters. This is because the exit holes of the adults are oval instead of round like those of most other beetles. Old stumps and logs of the Torrey Pine are often seen to be riddled with these holes, though the trees are not killed by Buprestids, but rather by members of the Scolytidae subfamily bark beetles. As is the case of most woodborers, these beetles are beneficial to the ecosystem by breaking down the dead wood and recycling its nutrients back to the soil. This species breeds in various Pines, Pinus spp. and Douglas fir, Psuedostuga menziesii, throughout the state. Eggs are laid in crevices of bark or in tree scars and larvae mine the cambium layer and then bore into bole of tree. First thoracic segment of larvae is much broader than following body segments.


Green Dock

Green Dock Beetle (Gastrophysa cyanea)

Adult: 5 mm

Family Chrysomelidae/ Subfamily – Galerucinae – Skeletonizing leaf Beetles

The Green Dock Beetle is common on Curly Dock, Rumex crispis, and related plants like the garden plant, Rhubarb, in spring. Members of the subfamily are called skeletonizing leaf beetles because the eat all but the main veins of the leaves. The elongated bright orange eggs are glued in place on the undersides of the leaves usually along the veins. In a few days the black larvae will appear, feeding and growing rapidly, often stripping all the foliage from the plants. When mature, the larvae crawl to the ground and pupate in the leaf litter. The dock beetles usually will be gone by summer, but there will be additional broods if food supplies persist. Note: The generic name was revised from Gastroidea to Gastrophysa.





Cylindrical Beetle (Cryptocephalus andrewsi)

Adult: 5 mm

Family Chrysomelidae/ Subfamily Cryptocephalinae – Cylindrical leaf Beetles

The generic name is taken from the Latin words crypto meaning hidden, and cephalus for head, thus, hidden head. The head of this beetle is not visible from above and can be retracted into the thorax when there is danger. Also, the legs can be retracted tightly up against the body. This is their way of protecting themselves. They fall to the ground if you try to touch them. There are many species of these little beetles and several live in coastal San Diego County. This particular kind favors the coastal sage scrub areas, and though the host plant is unknown, they are regularly found on buckwheat, Eriogonum fasciculatum. The larvae are case-bearers, as all of those in the subfamily Cryptocephalinae. The case is made of chewed plant material which is enlarged as the larvae grow and will eventually be their cocoon for when they pupate. The head is heavily armored and acts as a plug when the animal withdraws in times of danger.


Kelp beetle

Kelp Beetle (Phaleria rotundata)

Adult: 5-7 mm

Order Coleoptera/ Family Tenebrionidae – Darkling Beetles

A common inhabitant of the kelp wrack community from Baja California to central California. The larvae and adults feed on decomposing kelp.


Leaf-chafing Scarab

Leaf-chafing Scarab (Serica spp.)

Adult: 6-8 mm

Order Coleoptera/ Family Scarabaeidae – Scarabs

The c-shaped Serica larvae are root feeders of various shrubs like Manzanita and Ceanothus and are quite common on these and other plants on the reserve. The adults may defoliate fruit trees at times, feeding on flowers, buds and leaves. Serica are always attracted to lights and abundant during the summer months and may be readily separated from common “june” beetles by the iridescence of the body.

Chalepus spp

Leaf-mining beetle

Leaf-mining Leaf Beetle or Hispine Beetle (Chalepus spp.)

Adult: 3-4 mm

Order Coleoptera/ Family Chrysomelidae – Leaf Beetles/ subfamily Hispinae.

Common on flowers, especially of Asteraceae, sunflower family. Coastal sage scrub and inland. This species is at times abundant on the flowers of Isocoma venetus.


Mudflat Tiger

Mudflat Tiger Beetle
(Cicindela trifasciata sigmoidea)

Adult: 15-17 mm

Order Coleoptera/ Family Cicindelidae – Tiger Beetles

This species is common to salt marshes from coastal Baja California to central California and is also found around the Salton Sea. As all tiger beetles are, this one is a voracious hunter, preying mostly on brine flies of the family Ephydidae, but will take any prey which it can overpower. The mandibles, variously toothed according to species, are not only used for feeding, but are also used by the male of the species to grip the specialized female thoracic sulcus, or pit, during copulation. The males can often be seen riding the females en copula during late spring mating. The dark green coloring of this beetle is a good example of cryptic coloration, rendering this species almost imperceptible against the background of the dark mud on which it lives.

The remarkable larvae of tiger beetles live in vertical burrows which they enlarge as they grow. Clinging to the top of the burrow, they await passing prey with huge head held horizontally as to act like a lid. As the prey passes, they lunge, flipping backward, grasping it with their large mandibles to pull it into the burrow to feed. This action is aided by a pair of hooks on the fifth abdominal segment which secures the larva to the side of the burrow even with prey of superior strength.


Oak Twig Pruner

Oak Twig Pruner (Megobrium edwardsi)

Adult: 13 mm

Order Coleoptera/ Family Cerambycidae/ Tribe Hyboderinae – Twig Longhorn Beetles

Shown in image: Megobrium edwardsi (left), and Lampropterus cyanipennis

The beetles apparently begin their flights in March as evidenced in the pheromone traps. The one species of its genus, Pseudopilema hoppingi, occurs from California to Oregon where it is hosted in the larval stage by various species of oaks. Scrub oak, Quercus dumosa, is its larval host plant at the Reserve, and probably along with several other kinds of Longhorn Beetles and borers. Look for the little adults visiting the flowers of the warty-stemmed lilac, Ceanothus verrucosus, during the spring months.

A close relative of this beetle is the beautiful Lampropterus cyanipennis, from our local mountains. It is hosted by the white-flowered Ceanothus palmeri which is commonly seen near the summit of Mt.Laguna along Sunrise Highway. Watch for these hovering over the flowers of its host in spring and early summer.


Pictured Rove

Pictured Rove Beetle (Thinopinus Pictus)

Adult: 18-22 mm

Order Coleoptera/ Family Staphylinidae – Rove Beetles

These large flightless beetles can be seen in great numbers on the surface of the sand at Torrey Pines State Beach only at night where they prey on other insects of the kelp wrack community. During the day, they are burrowed beneath the sand. Though distributed on sandy beaches from Baja California to the northern California, the available undisturbed habitat has been greatly reduced due to removal of seaweed by various civic sanitation programs. The larvae are similar to adults in form and habits but lack the wing covers.


Pink glowworm

Pink glowworm (Microphotus angustus)

Adult: 8 mm

Order Coleoptera/ Family Lampyridae – Fireflies

These interesting beetles are most commonly found in summer months. Habitat is dry grassland and similar open sandy areas. The pink females are larviform and wingless and are found on the ground. At night they emit a bright green light near the caudal end to attract the winged males. The Larvae are similar to female, but often smaller. The food habits of this species are still unknown.


Sexton beetle

Red and black burying beetle (Nicrophorus marginatus)

Adult: 14-24 mm

Order Coleoptera/ Family Silphidae – Carrion Beetles

The species is common in lower elevations of Southern California, including Sorrento Valley, near Torrey Pines State Reserve, or wherever there is suitable carrion. Known also as sexton beetles, these insects specialize in burying dead rodents, snakes and other small animals. The male and female work together, securing the carcass below ground to prevent desiccation and carrion flies laying their eggs on it. They also clip away the hair to prepare it for egg-laying and to destroy any other insect eggs present. The pair will stay to care and defend their eggs and larval brood until they pupate to become adults. Two other species that are common to our area are Nicrophorus guttulus, the Yellow-bellied Burying Beetle, a black species with dense yellow hairs ventrally and Nicrophorus nigritus, the Black Burying Beetle which is similar to the latter but underside has black hairs.


Salt Panne Rove

Salt Panne Rove Beetle (Bledius flavipennis)

Adult: 4-6 mm

Order Coleoptera/ Family Staphylinidae/ Subfamily Oxytelinae – Spiny-legged Rove Beetles

This little species is an inhabitant of salt pannes in coastal salt marshes from Baja to Central California, and by their presence or absence, indicate the quality of the salt pannes and general health of the salt marsh and tidal flushing. With their legs armed with tibial rakes, they burrow into the fine clay soils creating a very extensive system of tunnels and egg chambers just below the surface.

The beetles are often truly intertidal when high tides wash over their areas. This flushing is vital to their survival bringing a renewal of the microscopic interstitial diatoms (single-celled algae) which are its food, as well as lowering the salinity of the soil. The beetles take small chunks of mud with the large mandibles, macerating it with their specialized mouth parts, called maxillae. These are blade-like and edged with a series of bristles and hairs to filter out the diatoms which they swallow whole. The waste mud is then taken to the surface and cast around the burrow opening, creating what is termed a midden, which eventually covers the opening. It is these middens that reveal their presence and numbers.


Fiddler crab

Another animal of the lower tidal zone, which feeds on the diatoms is the fiddler crab, Uca crenulata, – which also creates middens, or rather “chimneys” of emacerated mud about the top of its burrow, making an interesting case of convergent evolution of two unrelated species.

A number of other kinds of tiny beetles can be seen to regularly enter the tunnels of the rove beetles through the middens. These belong to the genera Tachys, 2.5 mm, and Microlestes, 1.5 mm, of Carabidae, predaceous ground beetles, and Anthicus and Ischyropalpus which average 2.5-4 mm of Anthicidae, the ant-like flower beetles. These invade the home of the rove beetles to plunder the eggs of their host. The scientific name; Microlestes, literally means little robber. Bledius is greatly enlarged and not to scale with the others pictured.


Stink beetle

Stink Beetle or Circus Beetle (Eleodes spp.)

Adult: 15-35 mm

Order Coleoptera/ Family Tenebrionidae – Darkling Beetles

These medium to large flightless beetles are probably as familiar to anyone as the “ladybug.” The forms are numerous in California with approximately 80-100 species described but separation and identification of particular species is all but impossible. The tooth on the front legs is a feature common to many of the species and so must not be relied upon. The common names are derived from the habit of many species to point their caudal ends skyward when disturbed. But contrary to common belief, they do not send out a cloud of noxious vapor. That trick belongs to the Bombardier Beetles of the genus Brachinus which belongs to the family Carabidae. Instead, the beetle just stands there in that amusing fashion until the danger passes, or if prodded or handled may exude a droplet of fluid from the caudal end. Reflexive bleeding from the joints, regurgitation and defecation are other chemical ways various arthropods will defend themselves. Regurgitation of “tobacco” juice is also used by the circus beetles and most other ground-dwelling Tenebrionidaes which will stain the fingers of the handler. The long and cylindrical larvae are heavily sclerotized, or armored, and live in or under rotten logs, leaf litter or similar situations where they feed on roots, fungi and other vegetable matter. They are often referred to as “false wireworms” by entomologists because of their resemblance to “wireworms” which are the larvae of the Click Beetle, Elateridae, family.

Trirhabda spp

Skeletonizing leaf beetle

Skeletonizing Leaf Beetle (Trirhabda species)

Adult: 5-6 mm

Order Coleoptera/ Family Chrysomelidae – Leaf Beetles/ Subfamily Galerucinae.

This beetle is abundant from spring to summer on Goldenbush, Isocoma venetus. The adults and larvae are found together feeding on foliage of this plant. Larvae are a dark metallic green, and adults are in life bright yellow with dark metallic green stripes. Many of the Trirabda spp. specialize in their choice of host plants, and another species is found on sagebrush, Artemisia californica.


Ten-lined June beetle

Ten-lined June Beetle (Polyphylla decimlineata)

Adult: 25-32 mm

Order Coleoptera/ Family Scarabaeidae / Subfamily – Melonthinae – Chafers

The Ten-lined June Beetle is certainly one of the most striking insects locally and always gets attention while it buzzes about, especially when it comes to lights on warm summer evenings, often erratically crashing into walls and windows. These are most common to the mountainous areas of San Diego County but are also found at Torrey Pines State Reserve. They belong to a group of scarabs known collectively as chafers, the ten-lined june beetle feeding on the foliage of a variety of conifers and broad leaf trees. The C-shaped larvae are subterranean and feed on roots, and according to the Forestry Service, often quite destructive to seedlings of various conifers.


Tumbling Flower

Tumbling Flower Beetle (Mordellistena spp.)

Adult: 2- 4 mm

Order Coleoptera/ Family Mordellidae – Tumbling Flower Beetles

Very small, these black or dark brown beetles with silvery pubescence can be seen on flowers feeding on pollen, especially on Eriogonum, Encelia, and Isocoma. They are dorsally wedge-shaped with the last abdominal segment pointed and protruding beyond the elytra. If disturbed, they tumble off the flower, giving them their common name. The slender, worm-like larvae are little investigated, but are known in part to be borers of the pith of various shrubs and weeds. There are around 150 species of Mordellistena cataloged in the U.S.


Wooly Ground Weevil

Wooly Ground Weevil (Dinocleus pilosus)

Adult: 8mm.

Order Coleoptera/ Family Curculionidae, Subfamily Cleoninae – Ground Weevils

Distributed throughout low elevations in San Diego County, the flightless Wooly Ground Weevil is usually hidden in the detritus of various plants of the coastal sage scrub, but seems most common beneath Flat-topped Buckwheat, Eriogonum fasciculatum. Because of this habit, it is seldom seen. And, as with all ground-dwelling, or epigeal species, they are extremely difficult to see if exposed or disturbed because of their habit of playing possum. In early spring the female burrows into the ground at the base of the plant and inserts her eggs into the root crown. The larvae bore into roots, and several other species have been destructive to crops. Note: The genus Apleurus has replaced Dinocleus due to recent revisions of the family Curculionidae.


Wooly Darkling

Wooly Darkling Beetle (Cratidus osculans)

Adult: 10-20 mm

Order Coleoptera/ Family: Tenebrionidae – Darkling Beetles

These beetles are for the most part nocturnal, though sometimes are seen wandering slowly on paths during the morning hours. The adults feed on plant detritus. The larvae are undescribed.

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