REFLECTIONS ON ARIZONA’S JEWEL SCARABS-Part 1

By Arthur V. Evans

I can still remember the very first Chrysina that I ever saw alive in Arizona. It was August 5, 1973 and Bob Duff and I had just set up our black lights in Bog Springs Campground in Madera Canyon. A soft-spoken man sporting a white t-shirt, khakis, and a crew cut came into our camp and introduced himself as Gayle Nelson. Only later did I discover that Dr. Nelson was one of the world’s leading authorities of jewel beetles (Buprestidae).

As the sun slowly set, the oaks all around us came alive with the buzzings of beetles. As Bob, Gayle, and I conversed, my eyes darted nervously this way and that  to each and every buzz in the bushes. This was my first night of black lighting in Southeastern Arizona’s Sky Islands and I did not want to miss any choice beetles! I did not know then that most of this crepuscular beetle activity was just the mating and feeding frenzy of several species of plain brown or black June beetles (Phyllophaga).

Just as darkness had completely descended upon us, I heard a bigger buzz followed by a thud. There on the sheet in front of me was an apple green beetle on its back with its lavender legs clawing at the air. I picked up the gorgeous beetle with my thumb and forefinger, only to discover that it’s powerful legs were tipped with needle-sharp claws. In spite of this surprisingly painful encounter, I was not about to let go of my very first Beyer’s jewel scarab, C. beyeri.

For several years afterwards the abundance of Chrysina at my lights were used as a barometer of sorts. I used their numbers, rightly or wrongly, as a way of measuring my success during many summer nights of black lighting in the mountains of Southeastern Arizona. Eventually my sensibilities began to change.

During the 1990’s, I collected specimens of C. beyeri and C. gloriosa alive and took them back to California for display in the Ralph M. Parsons Insect Zoo at the Natural History Museum of Los Angeles County, where I worked as the director. Both species thrived for several months on diets of oak leaves and juniper, respectively. Although the captive scarabs produced plenty of grubs, I made no effort to rear them to adulthood. To this day I regret not writing a formal description of the larva of Beyer’s jewel scarab and submitting it for publication; as of this writing, the immature stages of this species remain undescribed.

Now I regard species of Chrysina at my lights simply as old friends and no longer feel the urge to collect them in long series, if at all. I have heard stories of collectors and dealers with considerably less restraint collecting hundreds of specimens from the same mountain canyons, year after year. This annual carnage has led some people to wonder out loud whether or not Arizona’s Chrysina are in real need of some sort of legal protection. Nearly 30 years ago, Arnett and Jacques (1981) declared that both C. beyeri and C. gloriosa, which they mistakenly thought were the only species in the United States, were “…endangered and should not be collected.” However, on a warm and dry night in Madera Canyon this past July, all three species of Arizona’s Chrysina turned up at my light in good numbers. One species, C. gloriosa, was there in incredible abundance. Still, it would be worthwhile for a university or governmental agency to study the overall impact of intensive collecting on Chrysina populations in Madera Canyon and other popular collecting sites in southeastern Arizona.

Commonly known as jewel scarabs, the genus Chrysina is replete with incredibly beautiful, often metallic species. It includes nearly 100 species, most of which occur in Mexico and Central America. The four species in the United States are relics of a rich Neotropical fauna that expanded northward during more favorable (wetter) periods. For the past 10,000 years or so, these species were able to adapt to an increasingly warmer and drier climate by taking refuge in the high elevations of mountains.

 

Weldon Heald

 

The Southwest mountains inhabited by Chrysina are like stepping stones that bridge the gap between the temperate flora and fauna of the Rocky Mountains of the United States and the tropical biota of the Sierra Madre Occidental of Mexico. This archipelago of mountain “islands” in southeastern Arizona, southwestern New Mexico, and northern Mexico are surrounded by hot, dry desert “seas.” As such, they were dubbed “Sky Islands” nearly 60 years ago by the natural history writer Weldon Heald. Arizona’s Sky Islands are home to three species of Chrysina; the fourth American species is found in Texas.

All four of the American jewel scarabs were originally described in the genus Plusiotis. As a result of morphological and DNA evidence, the newer name Plusiotis was deemed redundant in relation to the older monicker Chrysina and it was formally synonymized by Dave Hawks (2001). The first species known in the United States, the glorious jewel scarab (C. gloriosa), was described by the father of American coleopterology, John L. LeConte in 1854. LeConte described this emerald-green and silver-striped species based on specimens collected at a copper mine in Texas that are now in the Museum of Comparative Zoology (MCZ) at Harvard.  These specimens were collected by the Secretary of the United States and Mexican Boundary Commission, Thomas Hopkins Webb. A physician from Rhode Island, Webb was appointed Secretary of the Commission in 1850, a position he held until 1854. In addition to his full-time position as Secretary, Webb enthusiastically collected insects, fishes, and reptiles and sent them to the leading authorities of the day. Later, he would become the secretary and principal executive officer of the Massachusetts Institute of Technology.

According to my friend, colleague, and Arizona scarabaeologist Bill Warner, C. gloriosa occurs in nearly all of the mountain ranges in at least the southern three-quarters of the state where their food plant, Juniperus, grows. Glorious jewel scarabs also occur in New Mexico, and Texas, as well as the Mexican states of Chihuahua and Sonora. With the onset of the summer monsoons, adults often spend their daylight hours feeding and resting on junipers; they are commonly attracted to lights at night, sometimes in large numbers.

In 1882, two years after LeConte’s death, another prominent coleopterist named George Horn described the second American species of Chrysina, LeConte’s jewel scarab (C. lecontei). His description was based on three examples now housed at the MCZ. These included one specimen from Tucson in the cabinet of England-born actor and entomologist Henry Edwards, another from LeConte’s cabinet collected in New Mexico by the curator of the insect collection at the University of Kansas, Professor Francis H. Snow, and a series in his own collection from Prescott, Arizona. Without any fanfare whatsoever, Horn ended his description by quietly dedicating the new species “to a friend.”

Warner notes that LeConte’s jewel scarab has essentially the same range in Arizona as the glorious jewel scarab, but that it is a bit more restricted to the higher altitudes where its food plant, the ponderosa pine, occurs. This species also occurs in New Mexico and the Mexican states of Chihuahua, Durango, Sinaloa, and Sonora.

 

Henry Skinner

 

The third American species of Chrysina was first exhibited by Horn on November 9, 1883 at a meeting of the entomological section of the Academy of Natural Sciences in Philadelphia. He presented two specimens collected in Rio Grande, Texas by his friend and Philadephia physician, Dr. Horatio C. Wood. Wood was a pioneer in American pharmacology who published numerous papers on pharmacology, physiology, and experimental therapeutics and taught neurology and internal medicine at the University of Pennsylvania. Early in his career Wood published papers in botany, entomology, and myriapodology. He traveled to the borderlands to collect specimens for the Smithsonian Institution and was one of the first white men to see the Grand Canyon. Wood recalled to lepidopterist Dr. Henry Skinner (1905) that the beetles he had given to Horn were either collected near El Paso, Texas, or in the valley of Tornellias [Tornillo] Creek at the great bend of the Rio Grande. The beetles were described in the minutes for the meeting as “pale malachite green, narrowly bordered with pale gold, the elytra are not striate, but with rows of fine punctures, the tarsi are beautifully violet.” Horn formally described Wood’s jewel scarab, Chrysina woodii, in 1885. These specimens are also housed in the MCZ. Horn noted that he saw another specimen in the Museum of the Jardin des Plantes in Paris. Wood’s jewel scarabs eat the leaves of walnut trees and are apparently diurnal, although some individuals are attracted to lights at night. It also occurs in Chihuahua, Mexico.

In 1905, Skinner, a gynecologist as well as co-founder and editor (1890-1910) of the Entomological News, described Beyer’s jewel scarab (C. beyeri) from four specimens collected in Carr and Miller Canyons in the Huachuca Mountains in southeastern Arizona. This handsome species first came to his attention the previous year when a specimen was sent to him from Reef in Cochise County. Reef was a mining camp in the southwest corner of Cochise County near the Mexican border. It was located in Carr Canyon in the Huachuca Mountains and was named for a noted landmark Carr Reef, an exposed and thick layer of rock. The site is now a campground in the Coronado National Forest. Skinner examined additional specimens presumably collected from the same locality by Beyer, Schaeffer, and Biederman. The Reef post office was officially relocated to Palmerlee (at the base of Miller Canyon) in December of 1904.

Gustav Beyer was a fur manufacturer from New York and an indefatigable insect collector who frequently travelled with his friend and Curator of Coleoptera at the Brooklyn Museum Institute of Arts and Sciences, Charles F. A. Schaeffer. Schaeffer spent a considerable amount of time collecting beetles at his three favorite haunts: Mt. Mitchell in North Carolina, the Lower Rio Grande Valley in Texas, and the Huachuca Mountains. Charles R. Biederman, a veteran of the Confederate Army and a resident of the Huachuca Mountains, was an ardent insect collector and is buried on his homestead in Carr Canyon. Before the advent of collecting Chrysina and other nocturnal beetles at light, both Biederman (1907) and another collector, Karl Coolidge (1911), noted a decided lack of success in obtaining specimens of C. beyeri, in spite of considerable searching about trees and in leaf litter. After finding a single specimen of C. beyeri in leaf litter, Biederman raked nearly two acres of leaves to find more beetles, but came up empty handed.

Beyer’s jewel scarab has the most restrictive distribution of all Arizona’s Chrysina and is known only from the Santa Rita, Patagonia, and Huachuca Mountains; it also occurs in the Animas Mountains of New Mexico and the states of Chihuahua and Sonora, Mexico. Adults feed on the leaves of Mexican blue oak, Quercus oblongifolia.

In 1915, Colonel Thomas Lincoln Casey, a noted and somewhat controversial coleopterist, described several species of Plusiotis, all of which have long been considered synonyms of the previously mentioned species.

Arizona’s jewel scarabs are not only popular with collectors and macro photographers, they also serve as wonderfully instructive subjects for scientific study, especially for scientists seeking to understand the physical qualities and adaptive significance of their brilliant colors. More on this subject will appear in the second and final installment of “Reflections on Arizona’s Jewel Scarabs.”

Sources:

Arnett, R. H., Jr, and R. L. Jacques. 1981. Simon & Schuster’s Guide to Insects. New York: Simon & Schuster. 511 pp.

Barnes, W. C. 1988. Arizona Place Names. Tucson, AZ: University of Arizona Press.

Biederman, C. R. 1907. Notes on Plusiotis beyeri Skinner. Entomological News 18: 7-9.

Burke, H. R. 2004. Notable Weevil Specialists of the Past. Charles Frederick August Schaeffer (1860-1934). Curculio 49: 5-7. Accessed on 26 September 2010 at: <http://www.texasento.net/Schaeffer.html#Burke>.

Calvert, P. P. 1926. The entomological work of Henry Skinner. Entomological News 37: 225-249.

Coolidge, K. R. 1911. Plusiotis beyeri Skinner. Entomological News 22: 326-327.

Evans, A. V. 2007. National Wildlife Federation Field Guide to Insects and Spiders of North America. New York: Sterling. 497 pp.

Hawks, D. 2001. Taxonomic and nomenclatural changes in Chrysina and a synonymic checklist of species (Scarabaeidae: Rutelinae). Occasional Papers of the Consortium Coleopterorum 4(1):  1-8.

Hawks, D. 2001. Checklist of Chrysina species (Scarabaeidae: Rutelinae: Rutelinae). (URL: http://www.unl.edu/museum/research/entomology/Guide/Scarabaeoidea/Scarabaeidae/Rutelinae/Rutelinae-Tribes/Rutelini/Chrysina/Chrysina-Catalog/ChrysinaC.html). In B.C. Ratcliffe and M.L. Jameson (eds.), Generic Guide to New World Scarab Beetles (URL: http://www-museum.unl.edu/research/entomology/Guide/Guide-introduction/Guideintro.html). Accessed on: 27 September 2010.

Horn, G. H. 1882. Notes on some little known genera and species of Coleoptera. Transactions of the American Entomological Society 10(1): 113-

Horn, G. H. 1885. New North American Scarabaeidae. Transactions of the American Entomological Society. 12: 117-128.

LeConte, J. L. 1854. Descriptions of the Coleoptera collected by Thos. H. Webb, M.D., in the years 1850-51 and 52, while Secretary of the U.S. and Mexican Boundary Commission. Proceedings of the Academy of Natural Sciences of Philadelphia 7: 220-225.

Leng, C. W. 1924. Gustav Beyer. Journal of the New York Entomological Society 32(4): 165-166.

Quincy, J. P. 1882. Memoir of Thomas Hopkins Webb. Proceedings of the Massachusetts Historical Society 19: 336-338.

Roth, G.B. 1939. An early American pharmacologist. Horatio C. Wood. 1841-1920. Isis 30(1): 38-45.

Skinner, H. 1905. Descriptions of new Coleoptera from Arizona with notes on some other species. Entomological News 16: 289-292.

© 2010, A.V. Evans

BEETLES OF EASTERN NORTH AMERICA: GOLDENROD SOLDIER BEETLE

By Arthur V. Evans

The goldenrod soldier beetle, Chauliognathus pennsylvanicus (DeGeer) (9-12 mm).

Late summer and early fall is the time for goldenrod soldier beetles, Chauliognathus pennsylvanicus (DeGeer). Adults feed on pollen from various flowers, especially goldenrod (Solidago), growing in gardens, parks, fields, meadows, and along roadsides and woodland edges.

These conspicuous beetles are often used as research subjects by scientists studying mating behavior, color polymorphism, dispersal, and genetics. This common and widespread species is found over much of eastern North America, ranging from southeastern Canada south to Florida, west to Colorado and Texas.

The margined leatherwing, Chauliognathus marginatus (Fabricius) (7-15 mm).

The head of these conspicuous and aposematically marked beetles is black and the pronotum is wider than long. By contrast, the head of the early spring/early summer margined leatherwing (C. marginatus), has a thick v-shaped mark, while the pronotum is longer than wide. The dark elytral spots of both species are either confined to the posterior half of elytra or extend along their entire length.

Dead and contorted soldier beetles are sometimes found on plants with their mandibles imbedded in stems or leaf edges. These beetles have succumbed to an infection by Eryniopsis lampyridum, a fungal pathogen that also attacks other insects. The open wings of the fungal victims are thought to enhance dispersal of the killer fungus’ spores.

© 2010, A.V. Evans

BEETLES OF EASTERN NORTH AMERICA: EASTERN HERCULES BEETLE

By Arthur V. Evans

The eastern Hercules beetle, Dynastes tityus (Linnaeus) (40.0 to 60.0 mm) is a large, spectacular olive-green animal mottled with irregular black spots. Well-hydrated individuals, especially those feeding or have just fed, are sometimes almost completely dark.

Males have a single horn on the head that is held in apposition to the largest of three on the pronotum. Together, these horns are used like forceps to dislodge rival males from sapping spots on the branches of ash trees. These sapping spots provide food for both sexes and are created by males specifically to attract hornless females.

Eastern Hercules beetles are found throughout much of eastern United States, from New York south to Florida, west to southern Illinois, western Arkansas, and eastern Texas. Both sexes are often encountered at lights, but seldom in numbers. However, large numbers of individuals are reported aggregating on ash (Fraxinus) or in tree holes used as breeding sites.

Larvae of eastern Hercules beetles.

The larvae develop and feed on rotting wood of various hardwoods, especially oaks, and occasionally pine. Large tree holes are sometimes used continuously as breeding sites year after year where the larvae feed on damaged rotten and crumbling heartwood; no harm is done to living trees. Their dark, rectangular fecal pellets are quite distinctive.

Pupa of a male eastern Hercules beetle.

The entire life cycle of eastern Hercules beetles may take two or three years, depending on conditions. Adults live several months in captivity on a diet of soft fruits cotton balls saturated with a 1:1 solution of water and maple syrup.

© 2015, A.V. Evans

BEETLES OF EASTERN NORTH AMERICA: TRICERATOPS BEETLE

By Arthur V. Evans

Species of Phileurus are characterized by their somewhat flattened, shiny black bodies, a sharply pointed clypeus, the smooth outer margins of the exposed mandibles, mouthparts covered below by a broad plate, a distinct groove running lengthwise along the pronotum, with a depression and a small bump just behind the head, and deeply furrowed elytra. Both adults and larvae are found in rotting logs and stumps. The larvae probably feed on decomposing wood and its associate fungi, while the adults are known to prey on insects and are attracted to lights at night.

The triceratops beetle, Phileurus truncatus (Palisot de Beauvois) (32-38 mm).

Sometimes called the “triceratops beetle,” Phileurus truncatus (Palisot de Beauvois) (32.0 to 38.0 mm) is a large, robust insect. Both males and females have large and distinct horns on the head. This species occurs from Virginia south to Florida, west to Tennessee and southeastern Arizona.

Adults are typically encountered at lights during the summer, but are seldom common. They occasionally enter homes through chimneys, which suggests that they may be associated with tree holes. The larval stages have yet to be described, but the pupae have been found  under the bark of a rotting oak stump.

© 2010, A.V. Evans

BEETLES OF EASTERN NORTH AMERICA: EASTERN RARE CLICK BEETLE

By Arthur V. Evans

The antennae of eastern false click beetles, Cerophytum pulsator (Haldeman) (5.4-8.5 mm), are comb-like (males) or saw-toothed (females).

The upper body surface of the eastern rare click beetle, Cerophytum pulsator (Haldeman), is dark reddish black to black, while the appendages and underside are usually lighter. The body is finely clothed with erect, yellowish setae. The elytra are somewhat dull, deeply grooved and finely, densely punctured.

Eastern rare click beetles are known from Pennsylvania to Florida, west to Illinois and Alabama. They prefer to live in mature, mostly deciduous forests. Adults are mostly active at night in spring and are collected at black light, in Malaise and Lindgren funnel traps, sweeping understory foliage, with rotten wood and bark, or in leaf litter. When held, they can “click” and are capable of jumping as a form of escape behavior.

© 2010, A.V. Evans

BEETLES OF EASTERN NORTH AMERICA: FIRE-COLORED BEETLE

By Arthur V. Evans

The fire-colored beetle, Neopyrochroa femoralis (LeConte) (13-19 mm), is easily distinguished from other large pyrochroids in eastern North America by its black and orange legs.

The fire-colored beetle Neopyrochroa femoralis (LeConte) is easily distinguished from the only other large pyrochroid in eastern North America, N. flabellata (Fabricius), by its black and orange legs. The male has branched antennae and lacks a horn on its head. Adults are found under bark or at lights at night in spring and summer. This species occurs from Ontario and Quebec south to Georgia, west to eastern Nebraska and Texas.

© 2010, A.V. Evans

BEETLES OF EASTERN NORTH AMERICA: BUMBLE FLOWER SCARAB

By Arthur V. Evans

This bumble flower scarab, Euphoria inda (12-16 mm), resembles a bee in flight, right down to the buzzing sound as it flies low over the ground.

The bumble flower scarab, Euphoria inda (Linnaeus), is the most widely distributed species of Euphoria in North America, ranging from Quebec south to Florida, west to British Columbia, Oregon, Colorado, and southeastern Arizona. The head and pronotum are mostly black, while the elytra are yellowish-brown with variable black spots. The dorsal surface is shiny or dull.

The larvae develop in various accumulations of plant materials, rotten wood, and within the thatched nests of ants in the genus Formica. Adults emerge from their earthen pupal cases in late summer, overwinter, and become active again the following spring. They are often found flying close to the ground in the morning until midday, especially over piles of grass, edges of haystacks, compost piles, manure, and other plant debris. They are sometimes found in numbers drinking sap from wounds on tree trunks and exposed roots, or feeding on various flowers and ripe fruits.

© 2010, A.V. Evans

Note: The “Beetles of Eastern North America” series features descriptions that will appear in a slightly abbreviated form in my upcoming field guide to be published by Princeton University Press.

WINTER DARK FIREFLIES

By Arthur V. Evans

Today was cool, gray, and blustery–not exactly what I would call ideal conditions for finding insects. Nevertheless, I set out for the woods along Jordans Branch in Bryan Park here in Richmond, Virginia in hopes of finding early spring species to photograph. I ambled down a trail through a stand of holly toward a mixed woodland of loblolly pine and various hardwoods. As I knelt down to inspect the trunk of a pine snag, a faintly beetlish outline partially hidden in a crack in the bark caught my eye.

The winter dark firefly, Ellychnia corrusca, is mostly dull black with yellow, orange, or reddish arched bands along the sides of their midesection.

It was a winter dark firefly, Ellychnia corrusca. Flat and soft-bodied, the beetle measured slightly more than one half inch in length. It remained motionless until I gently coaxed it out of its hiding spot with a pine needle for a better look.

Winter dark fireflies are mostly dull black, but the sides of their flattened, shield-like midsections are marked with yellow, orange, or reddish arched bands. Their soft, pliable wing covers are clothed in short, fine, golden hairs.

Mature larvae pupate in dead logs, especially pines. Adults emerge in late summer and fall and are sometimes encountered on trees or on the flowers of goldenrod and other asters. As temperatures begin to drop, they seek protected places under bark for the winter. The beetles reappear on late winter and early spring days, either resting on bark or circled around sap flows on maples like cattle around a trough.

Like their more familiar cousins of summer, winter black fireflies are bioluminescent, at least for a while. Both the larval and pupal stages produce their own light. Even freshly emerge adults maintain this youthful glow, but as the beetles grow older they lose their light-producing organs.

Mating winter dark fireflies are not an uncommon sight. Their courtship involves two stages. First, the male climbs on the back of the female while constantly touching her with his antennae and mouthparts. This activity alone may last for up to half an hour. Afterward, the couple consummates their relationship by joining their bodies as they face away from one other. Sometime during the next hour or so, the male transfers a protein-packed packet, or spermatophore, to the female. Pairs of beetles sometimes remain joined together this way for up to an entire day. Over the next several days the female will slowly digest the spermatophore inside her body and store it as a source of energy in her body. Both males and females will mate several times before dying in late spring or early summer.

When attacked, these beetles exude a bitter fluid from their leg joints. This defensive strategy, known as reflex bleeding, is also practiced by other species of lightningbugs.In spite of their chemical defenses, phorid flies attack winter dark fireflies and their kin. Just how the flies locate their hosts is unknown, but their maggots develop inside the beetle, killing their beetle host as they emerge to pupate.

Recent studies suggest that winter dark fireflies are not a single species, but represent a complex of closely related, yet undescribed species that inhabit most of eastern North America. The taxonomy and natural history of these handsome, delicate, harbingers of spring would make an excellent study for a student looking to make a significant scientific contribution to the study of North American beetles.

© 2010, A.V. Evans

THE FOREST CATERPILLAR HUNTER, Calosoma sycophanta, IN VIRGINIA

By Arthur V. Evans

In July of 2008, while conducting a beetle survey of the Bull Run Mountains Natural Area Preserve in Fauquier and Prince William counties in Virginia, I found numerous metallic green elytra scattered along a foot trail winding through an oak woodland on a west-facing slope. The area had been heavily infested with larvae of the gypsy moth, Lymantria dispar, as evidenced by thousands of larval exuviae and pupal cases that festooned the trunks of oaks and other hardwood trees.

At first glance, I thought the beetle remains were those of the indigenous caterpillar hunter or fiery searcher, Calosoma scrutator, a common, brightly colored, and widespread carabid beetle found in the mountains and lowlands of Virginia. Closer inspection revealed that the elytra were much brighter and more yellow than those of C. scrutator and lacked the characteristic coppery red margins.

Further searching in the area produced a very fragile, yet nearly intact specimen ensnared in an abandoned spider web. The pronotum of this specimen was mostly black with metallic blue along the margins, rather than bluish with violet or coppery yellow green borders typical of C. scrutator. Of the five other species of Calosoma known in Virginia, only C. wilcoxi has entirely metallic green elytra, but it is smaller and much duller than either C. scrutator or the silk-wrapped remains in question. (Figure 1).

Figure 1. The Virginia species of Calosoma (from top to bottom, left to right): C. calidum (F.), C. externum (Say), C. frigidum Kirby, C. sayi Dejean, C. scrutator F., C. sycophanta (L.), and C. wilcoxi LeConte. The scale bar equals 5.0 mm. © 2009, Chris Wirth.

I soon realized that what I had in my possession were the remains of a European species, the forest caterpillar hunter, C. sycophanta. Long known as an important predator of gypsy moth larvae in France, 4,046 of these beetles were imported into the United States between 1905 and 1910, most of which were released in New England to combat outbreaks of two European species of lymantriids: the gypsy moth and the browntail moth, Euproctis chrysorroea.

In the United States, the forest caterpillar hunter is established in Connecticut, Maine, Maryland, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Rhode Island, Vermont, and Washington. They have been released in Delaware, Michigan, Washington, and West Virginia, but they have yet to become established in these states. In spite of releases on Vancouver Island, British Columbia, Quebec, New Brunswick, and Nova Scotia, the forest caterpillar hunter does not appear to be a permanent resident in Canada either.

Both the adults and larvae climb trees to attack and eat caterpillars and pupae of gypsy moths and other species. Adult males are more likely to be found on tree trunks, while females tend to remain on the ground. Based on observations in the laboratory and in the field, both sexes are active day and night. Males tend to be more conspicuous as they spend most of their time actively searching for mates. The more secretive females spend much of their time buried in the soil and hidden among leaf litter to feed and lay eggs.

Adult activity coincides with the larval activity of the gypsy moth. Beetles emerge from their overwintering sites in June to search for prey and mates, although some beetles may remain dormant for up to two years. Although adults are strong and agile fliers capable of leaving their overwintering sites behind to search for high populations of caterpillars, their appearance at new outbreaks of gypsy moths is by no means certain. In fact, beetles released as part of biological control programs often remain near their release site.

Forest caterpillar hunters will attack a variety of other caterpillar species, but are most abundant where populations of gypsy moth caterpillars are high. They remain active for about a month, re-enter the soil, and remain there until the following spring.

Adult predation is not this species’ primary impact on gypsy moth populations. It’s greatest impact is through larval production and the voracious appetites of the beetle’s larvae for mature caterpillars and pupae. The ability of adult beetles to reproduce is directly dependent upon the availability of high densities of gypsy moth caterpillars, especially since females require sufficient protein to ensure successful development of their eggs.

Eggs are laid in the soil beginning in early July and hatch in 4-7 days. The larvae climb trees in search of caterpillars and pupae. The remains of pupae attacked by beetle larvae have characteristically large and jagged holes. Mature beetle larvae seek pupation sites in the soil. The entire life cycle, from egg to adult, takes about seven weeks. In Connecticut, adults are known to live three to four years.

Anecdotal evidence suggests that forest caterpillar hunters are potentially important predators of gypsy moth larvae and pupae, but there is still much to learn. Nearly all of the information on the ecology and behavior of C. sycophanta was gathered during the brief period of adult activity that coincides with gypsy moth outbreaks, but little is known about the ecology of this species between outbreaks.

Many thanks to Chris Wirth for the wonderful color plate. This essay is excerpted from Evans, A.V. 2010. The forest caterpillar hunter, Calosoma sycophanta, an Old World species confirmed as part of the Virginia beetle fauna (Coleoptera: Carabidae). Banisteria [2009] 34: 33-37. The full article is available at http://fwie.fw.vt.edu/VNHS/banisteria/banisteria.asp.

©2010, A.V. EVANS