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

SKY ISLANDS, DESERT SEA-Part II, Hornworm Highway

By Arthur V. Evans

Charged by the onset of the summer monsoons in July or August, the arthropods of Arizona’s Sky Islands and desert seas are stirred into action.  The sudden and intense infusion of life-giving moisture triggers a flush of activity: eggs hatch, hungry larvae gobble up new leaves, adults are released from their earthen or wooden chambers, eager to mate and reproduce.  It is this marvelous intensity of arthropod activity that has drawn me to the mountains, desert scrub and grasslands of southeastern Arizona for nearly 40 years.

My earliest impressions of Arizona’s desert seas were formed by numerous overland trips from California in the 1970’s. Within minutes of crossing the Colorado River, the first saguaros would greet us, stationed like lone sentinels high on the rocky ridges of the Dome Rock Mountains. Although these giant columnar cacti have become symbolic of all arid regions of the southwest, they are strictly indigenous to the Sonoran Desert. These and other nearby desert ranges are capable only of supporting plants and animals adapted to fleeting amounts of rain. The summer monsoons, even at their height, seldom penetrate this far north and west.

Driving east from Gila Bend to the Maricopa Mountains, the stands of saguaros become taller and denser. Compared to the deeply pleated trunks of their western brethren, the almost bulging flesh of these plants is a clear sign of increased precipitation. The saguaros’ spongy inner tissues rapidly expand to absorb and store seasonal supplies of water as a hedge against the inevitable drought ahead.  Even the spiny ocotillo stand taller and greener here, surrounded by dense thickets of palo verde.  Here all living things enjoy the increased benefits of living under the blanket of the summer monsoons.

Another sure sign of increased rainfall is the sporadic population explosion of green and black-striped hornworms, caterpillars of the white-lined sphinx moth, Hyles lineata. Dozens to hundreds of these insects race across the hot, blistering highway in a scramble for tender desert greens. Some years there are so many of the caterpillars that the pavement becomes slick with their crushed bodies. At night marauding three-inch-long shield-backed katydids of the genus Capnobates rip chunks of sun-dried caterpillar from the road and grind them up with their powerful jaws, while scores of ants carve up the leftovers and carry them back to their underground brood.

© 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.

LUNA MOTHS ARE ON THE WING

By Arthur V. Evans

The luna moth, Actias luna (Linnaeus). Although the luna moth is native to North America, most of its relatives live in Asia.

Last night, while black lighting for beetles on a cool and still spring night in the Bull Run Mountains in northern Virginia, I was treated to an incredible display of luna moths, Actias luna (Linnaeus). Within an hour of turning on the lights, a baker’s dozen of these marvelously green and ornately tailed creatures had settled on the sheet and nearby tree trunks. Such a sight made me feel quite giddy and brought back a flood of memories of some of my earliest encounters with other spectacular insects as a young naturalist.

The first luna moth that I ever saw in Virginia flew through an unscreened upstairs window. It looked like a soft, green bat as it circled the light at the top of the stairs. It was all that I could do to keep it from being gobbled up by our cats!

They range throughout the hardwood forests of eastern North America. Luna moths were long known to naturalists by the time they were described by Carolus Linnaeus in 1758. The earliest known reference to luna moths in North America was in a note published James Petiver 1700, who had based his comments on a specimen collected in Maryland.

Like other moths and butterflies, the wings of luna moths are covered with scales that make up their colors and patterns.

Luna moths typically emerge from their cocoons in the morning. Powerful fliers, they are often attracted to porch lights and well-lit storefronts. There is only one generation produced in the northern parts of its range and two or three generations are produced in the south. Moths emerging in spring are bright green or blue-green with prominent reddish-purple margins on the outer forewings, while summer broods tend to be more yellow over all with yellowish outer wing margins.

Mating takes place after midnight. Pairs of luna moths sometimes remain coupled until the following evening. Eggs are laid singly or in small batches on upper and lower surfaces of leaves and hatch in about a week. The ravenous and solitary caterpillars feed on the leaves of a wide range of hardwoods, including birch, hickory, walnut, persimmon, and sweetgum. Different populations of luna caterpillars show regional preferences for host plants.

The feathery, or pectinate antennae of the male luna moth are covered with sensory pits that enable to them to detect just a few molecules of the pheromones released by receptive female moths.

Only when they are ready to pupate do the mature caterpillars wander away from the food plant. Cocoons are spun on the ground among the leaf litter at the base of the host tree. Each cocoon consists of a single layer of thin and papery silk that incorporates one or more leaves.

Sightings of the luna moth’s spring brood will still be possible over the next few weeks. Look for them at lights near wooded areas and you just might be treated to a glimpse of one of North America’s most spectacular animal species.

© 2010, A.V. Evans

SKY ISLANDS, DESERT SEA-Part 1

By Arthur V. Evans

“…some of the earth’s most interesting “islands” are nowhere near oceans or lakes. They are strictly land islands but with a climate, vegetation, and animal life as different from their surroundings as if they rose from some remote sea.”

Weldon Heald in Sky Islands

A conservationist and journalist, Weldon Heald coined the term “Sky Islands” nearly 60 years ago to describe the archipelago of mountain ranges spanning the gap between the Rocky Mountains and the Sierra Madre Occidental of central Mexico. Made up of more than 40 isolated mountain ranges, the Sky Islands cover two countries in the states of Arizona, New Mexico, Sonora and Chihuahua. The diversity of flora and fauna inhabiting this region is unmatched in temperate North America. Warmer than the Rocky Mountains and drier than the Sierra Madre Occidentale, these unique and isolated mountain ranges support a wealth of temperate and tropical arthropod species.

The mouth of Cave Creek Canyon, Chiricahua Mountains, Cochise County, Arizona.

The Arizona Sky Islands consist of the Santa Rita, Rincon, Huachuca, Santa Catalina, Whetstone, Bobaquivari, Pinaleño, and Chiricahua Mountains. Climbing thousands of feet into the sky, these lush mountains and their canyons stand in stark contrast to the surrounding lowlands. It is the sheer mass and altitude of these ranges that keeps their peaks and canyons much cooler and wetter than the surrounding desert scrub and grasslands. On average, mountain temperatures drop 4 º Fahrenheit for every 1,000 feet of elevation, while at the same time, annual precipitation increases by four inches. These moisture and temperature gradients create life zones that support populations of arthropods poorly adapted for survival in the relatively harsh, dry environs below. Unable to migrate across this “desert sea,” many of the arthropods inhabiting Arizona’s Sky Islands have been marooned for hundreds of centuries.

© 2010, A.V. Evans

FALCATE ORANGETIPS

By Arthur V. Evans

After a few false starts spring has finally arrived here in central Virginia, and not a moment too soon. In hopes of seeing some examples of the early spring insect fauna, I recently set out on a warm, sunny day for the James River Park near the 42^nd Street entrance.

The orange and slightly hooked wing-tips were the unmistakable field marks of the male falcate orangetip, Anthocharis midea, the only species of orangetip butterfly found in the eastern United States.

The latest floodwaters from spring rains had only just receded, leaving a thin and dusty film of silt and debris high above the river’s usual channel in the park. Just past the flood residue, small plants had raised their tiny blossoms high to lure the season’s first pollen- and nectar-loving insects.

As I wandered upriver toward the Nickle Bridge, a flash of white with a hint of rich orange crossed my path. It slowly yet deliberately flitted about the freshly emerged sprigs of green that populated the edges of the path before finally settling for just a moment or two on a small flower. The orange and slightly hooked wing-tips were the unmistakable field marks of the male falcate orangetip, Anthocharis midea, the only species of orangetip butterfly found in eastern United States.

The females lack the orange patch, but are otherwise similar in appearance to the males. The wings of both sexes are mostly white; the underside of the hind wing bears a finely marbled yellowish-brown pattern. From tip to tip, their wings span no more than one-and-a-half inches across.

Falcate orangetips are among the first butterflies to emerge from their pupae in spring. Widespread in Virginia, they are found in a variety of habitats, including parks, rocky mountain outcrops, open deciduous and mixed pine-oak woodlands, sandhills, and floodplain forests, especially along stream and river courses.

Females lay their greenish-yellow eggs singly on the flowers of various cresses and other members of the mustard family. The eggs soon turn red and hatch into ravenous larvae that devour mostly seed pods, buds, and flowers, and not leaves. Because of the limited number of reproductive structures on each food plant, larger caterpillars will not hesitate to eat their smaller brethren to reduce competition for meager food resources.

Mature caterpillars are green or blue-green and sprinkled with shiny dark plates bearing short bristles. A yellow stripe runs down the length of the back, while a broad white stripe runs from the head and along each side and meet on its backside. The winter is spent, sometimes two, as a narrow chrysalis that is sharply pointed on both ends.

Don’t hesitate to look for these attractive insects in an open woodland or bottomland forest near you. By early June the falcate orangetips will all be gone, and you will have to wait until the following spring for the next generation to once again make their brief and welcome appearance as heralds of spring.

© 2010, A.V. Evans

TRUE CONFESSIONS

By Arthur V. Evans

Every now and again I am asked what is my least favorite insect or spider. I really don’t have an answer for this question. But I can say, without hesitation, that my least favorite arthropod is the centipede.

Don’t get me wrong. I think that centipedes are fascinating animals, but every time I happen upon one of the larger species in the Order Scolopendromorpha, I can feel the hair on the back of my neck stand up and a cold chill run down my spine.

A centipede has never bitten me, so my discomfiture is not based on personal experience. But I do know what the larger species are capable of in terms of delivering a painful, yet non life-threatening bite with their powerful fanglike front feet, or gnathopods. Combined with their speed and lithe bodies, centipedes just set me on edge.

Scolopendra heros from southeastern Arizona dining on a young mouse. Note the thick, black gnathopod next below the head.

Scolopendra heros, the largest centipede species in the United States, measures in at a whopping 6.5 inches (16.5 cm). They range from central and southern Arizona east to southwestern Missouri, Arkansas, and Louisiana. This species is extremely variable in color. During the summer, adults are active around the clock and are easily seen in the headlights of a moving car as they cross the highway at night with their fore bodies bobbing up and down.

I used to collect these big bruisers to put on display in Insect Zoo at the Natural History Museum of Los Angeles County. While on the road, I checked their containers often to make that the lids were securely fastened. My travelling companions were regularly warned that if a lid accidentally came off and a centipede was on the loose, I would immediately abandon the vehicle.

Yesterday, while collecting beetles in the Zuni Pine Barrens of the Blackwater Ecological Preserve, I committed a potentially serious faux pas in the field by peeling back some loose bark of a dead loblolly pine tree that was leaning directly over my head.

Hemiscolopendra marginata occurs in Missouri, Oklahoma, and Texas east to Virginia and Florida; it is absent in most of the Appalachians.

Out of the corner of my eye, I saw a blue-green centipede, Hemiscolopendra marginata, fall from its once-secure perch, its two-inch long body trunk twisting in the air in an effort regain some sort of foothold. Before I could react, it slid across my forearm to the leaf litter below. Or so I thought.

For several seconds my mind raced. What if it didn’t fall on the ground? What if it or another centipede landed on my shoulder? What should I do? What if it got inside my shirt? My now fevered brain began imagining the centipede sinking it’s gnathopods into the soft and sensitive skin of my neck. Or worse.

I stood perfectly still in the bright spring sun filtering through the tall and slender pines, my body tingling all over in anticipation of anything from a crawling sensation to a stabbing pain. The centipede was nowhere to be felt or found. Still, it took me several more minutes to become convinced that my person was centipede-free and begin to feel a sense of relief.

Recounting this event a full day later still gives me the heebie-jeebies!

© 2010, A.V. Evans

CARPENTER BEES ARE BORING!

By Arthur V. Evans

It's spring and the eastern carpenter bees, Xylocopa virginica, are back!

The usual suspects of spring are all around me once again, including large, buzzing, blue-black eastern carpenter bees, Xylocopa virginica. They are noisily patrolling dead limbs and wooden structures in our neighborhood as they search for mates and nesting sites. Unlike the social honey bee imported from Europe, carpenter bees are solitary creatures native to North America. The bees buzzing around now reached maturity last summer. Back then they stretched their wings for a bit before tucking themselves away for the winter deep within the recesses in the very nest chamber where they had grown up.

Unlike the dark-faced female, the male Xylocopa virginica has a white "face."

White-faced and stingless, males are very territorial and spend much of their time claiming prominent flowering plants and bare patches of ground as their own. They aggressively drive off other bees and insects and often face-off with unsuspecting humans that unwittingly venture into their territory. The territorial borders of male carpenter bees are quite fluid and change from day-to-day. Amorous males regularly patrol flowers in search of females. Courtship involves lots of loud buzzing and aerial acrobatics, with the pair flying apart and coming together several times.

Dark-faced females are capable of delivering a painful sting, but are relatively docile. They chew their nest tunnels in dead trees, logs, or unfinished wooden structures, especially those with southern or eastern exposures. Females will consider exposed rafters, old house frames, picnic tables, rail fences, posts, trellises, and other exposed wood surfaces as potential nest sites.

With their powerful jaws working non-stop day and night, female carpenter bees will chew a perfectly round entrance hole that is about one half-inch in diameter. After tunneling in about one body-length, the tunnel turns sharply to the left or right at a 90º angle to follow the timber’s grain. They may construct two or more parallel tunnels from the main entrance that measure up to 14 inches long, each slightly wider than the entrance in diameter.

Sometime in May or June, the first egg is laid on a doughy pill of pollen about the thickness of a kidney bean at the end of a blind tunnel. The provision of pollen serves as the sole food source for the developing bee grub. The surrounding wood in the tunnel is then chewed into a fine pulp for form a disk-shaped partition that seals the egg off in its own cell. Each tunnel may have up to 6-8 cells.

Carpenter bees do not eat wood, but rely instead on flowers for nourishment. As the adults forage for pollen and nectar, they will mark each flower that they visit with a repellant chemical, or pheromone, that lasts up to 10 minutes. By skipping marked flowers carpenter bees can save time and effort by avoiding flowers recently depleted of their resources by other carpenter bees.

Tolerance is the key to appreciating carpenter bees. In spite of all the sawdust created by their nesting activities, they seldom cause severe damage. What damage they do cause is easily offset by their pollination services. Our gardens, fields, orchards, and forests would not be nearly as productive if it were not for their efforts and those of other pollinators. Besides, whether they are energetically visiting flowers, zooming through the air in conjugal bliss, or tirelessly engaged in nest-building, carpenter bees are just darned fascinating animals to watch!

© 2010, A.V. Evans