Archive for Virginia

A BEVY OF BUCKEYES

Posted in Butterflies, Insects, Virginia with tags , , , , , , on September 15, 2010 by Dr. Art Evans

By Arthur V. Evans

For the past month or so, Virginia has been awash with the Common Buckeye, Junonia coenia. The name Junonia is derived from the diminutive form of the Greek Juno, Zeus’ consort, while the specific epithet, coenia, comes from the Greek kionos meaning common. With six distinct eyespots on their wings, these handsome and energetic insects cannot be confused with any other butterfly species in the Commonwealth.

Their rapid, low, and somewhat erratic flight consists of fluttering strokes occasionally interrupted by meandering glides usually of no more than a foot off the ground. When alarmed, Common Buckeyes are capable of taking to the air in a rapid and sustained flight. They sip nectar from a variety of flowers and frequently rest in open, sunny spots in neighborhoods, parks, wetlands, fields, roadsides, and other open habitats with plenty of low-growing vegetation.

The orange-headed and metallic blue-spined caterpillars are highly variable in color and pattern. They feed on plants in several families and are especially fond of those in the snapdragon (Scrophulariaceae) and acanthus (Acanthaceae) families.

Although they occur throughout the United States, Common Buckeyes only persist in the frost-free southern and eastern halves of the country; individuals observed in the Great Lakes States, New England, and southern Canada are migrants. In eastern United States, these butterflies are in evidence throughout the winter in Florida and the coastal regions of southeastern and Gulf States.

© 2010, A.V. Evans

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LUNA MOTHS ARE ON THE WING

Posted in Insects, Moths with tags , , , , , , on April 21, 2010 by Dr. Art Evans

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

FALCATE ORANGETIPS

Posted in Butterflies, Environment, Insects, Virginia with tags , , , , , , , on April 5, 2010 by Dr. Art Evans

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 42nd 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

Posted in Centipedes, Environment, Musings with tags , , on April 3, 2010 by Dr. Art Evans

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

BELLY UP TO THE GRAVEL BAR FOR TOAD BUGS

Posted in Aquatic, Defense, Insects, Predators/parasites/parasitoids, True bugs, Virginia, Virginia State Parks with tags , , , , on March 28, 2010 by Dr. Art Evans

By Arthur V. Evans

One of my favorite haunts for insect photography is a small and unassuming gravel bar located just downstream from the dam that keeps the Swift Creek Lake within its banks in Pocahontas State Park, Virginia.

The toad bug, Gelastocoris oculatus, is widely distributed throughout southern Canada and most of the United States.

Gravel bars are tough places to live. Their surfaces can reach blistering temperatures or be completely inundated by flooding waters. Still, they support insects adapted to live under such harsh conditions that are seldom found anywhere else.

Many larger species spend their days hiding under stones and their nights foraging for food and mates. Some smaller species spend their entire lives comfortably wedged between the narrow, wet spaces between pebbles and coarse grains of sand. And still others are just passing through.

Not long ago, with a rushing stream at my back, I slowly knelt down on thankfully padded knees to recalibrate my focus on this universe wrought small. It took me of bit of time and patience to get my head out of the hustle and bustle of modern-day life, shake off the city with its noise and congestion, and begin to really see and appreciate the tiny inhabitants of this rocky shoal.

Bit by bit I took in my surroundings. Suddenly, a bit of movement drew my eyes toward a small embankment. I kept staring at the spot as I inched toward it, hoping to see whatever it was moving again. But it didn’t. Then it did, and I zeroed in on the spot. Just as the short, warty bug with bulging eyes came into focus, it jumped away. It was a toad bug, Gelastocoris oculatus.

It was as if I had just seen an old friend. I can still remember my very first encounter with this species along the edges of Little Rock Creek that meandered slowly out of the San Gabriel Mountains to the southern fringes of the Mojave Desert in Southern California. This species of toad bug is widely distributed throughout southern Canada and most of the United States.

The rough bodies of toad bugs are usually dull and mottled with brown and black. The base colors range from almost entirely yellowish, reddish-yellow, grayish-black, to nearly black. As a result, toad bugs are masters of the disappearing act.

Their front legs resemble those of a praying mantis, only shorter and chunkier. And like praying mantises, toad bugs are voracious predators and use these legs to capture small insects.

In Virginia, both larvae and adults live gregariously in a variety of habitats along the muddy, sandy, or gravelly margins of ponds, streams, and rivers. Overwintering adults appear in spring to feed and mate.

From May through September each female lays a dozen or so white eggs at a time in the sand, probably 200 or more in their lifetime. The eggs hatch in about two weeks; another two or three months are required before the larvae reach adulthood.

The toad bug eventually abandoned the gravel bar and disappeared into some low herbaceous growth nearby. I turned to find a small coppery ground beetle with bulging eyes, bright green legs, and patches of purple on its back running across the gravel, but this is a story for another time.

© 2010, A.V. Evans

ALTERNATIVE SPRING BREAK AT THE VCU RICE CENTER

Posted in Education, Environment, Insects, VCU Rice Center, Virginia with tags , , on March 26, 2010 by Dr. Art Evans

By Arthur V. Evans

© 2010, J. Barton

Last week, I met a group of very dedicated and enthusiastic students from the Virginia Commonwealth University and Virginia Wesleyan College at the VCU Rice Center in Charles City County. They had spent the last several days participating in various activities as part of this year’s Alternative Spring Break. Sponsored by the Chesapeake Bay Foundation, Alternative Spring Break provides students with an opportunity to explore and give to their community by providing a week’s worth of environmental and conservation projects, such as planting trees, tending gardens, tidying  up parks and wildlife refuges, and stream cleanups. At the Rice Center, some of the students would have the opportunity to help me with my insect survey.

© 2010, J. Barton

After an impromptu presentation about my survey and some of the methods used to trap insects, my team of volunteers was ready to get started. They grabbed tools and traps and set out for the first trap site. Working like a well-oiled machine and with minimal direction, they quickly established two sets of Malaise, Lindgren, and pit fall traps in less than two hours.

Malaise trap. © 2010, A.V. Evans

What is a Malaise trap you ask? It’s like a tent with its walls on the inside and is specifically designed to capture flying insects, day or night. Upon hitting the internal nylon panels, most insects will eventually work their way up into a collecting container partly filled with alcohol. Malaise traps are usually used to catch flies, bees, and wasps, but other kinds of insects are captured, too. They are typically placed along roads, trails, streams, or forest edges. Up to 1,000 insects a day may be captured in a good site.

Lindgren funnel trap. © 2010, A.V. Evans

Lindgren funnel traps are designed to attract and capture wood-boring beetles and other insects that alight on tree trunks. They consist of a rain and debris guard with a dozen black plastic funnels suspended directly underneath. Attached to the bottom funnel is a specimen receptacle. Each trap is fitted with chemical lures that simulate the odors given off by dead and dying trees. Insects attempting to land on the trap fall down the funnels and into the receptacle at the bottom. Foresters use Lindgren funnel traps to monitor pest insects in stands of managed timber, especially bark beetles.

Pit fall traps connected by drift fences of metal flashing capture small crawling animals,

Pit fall traps. © 2010, A.V. Evans

especially insects and other arthropods. At the end of each drift fence is a single pit fall trap consisting of two 16-ounce plastic drink cups nested in one another and sunk so that the tops are flush with the soil surface. The inner cup is partly filled with environmentally “friendly” antifreeze (propylene glycol). Each cup is covered with 1/2” mesh and flashing to keep out both vertebrates and rain.

© 2010, A.V. Evans

Thank you so very much to all the students who joined me on that wonderful day. Not only did you help get the job done, you also inspired me with your camaraderie, energy, and sense of purpose.

© 2010, A.V. Evans

MANTIDFLIES GET A LEG UP ON SPIDERS

Posted in Insects, Predators/parasites/parasitoids, Virginia with tags , , , , , on March 17, 2010 by Dr. Art Evans

By Arthur V. Evans

A few years back, on a warm muggy evening in September at the Savage Neck Natural Area Preserve on the Eastern Shore of Virginia, I was checking a light trap designed specifically to lure night-flying insects. As the beam of my headlamp swept over nearby shrubbery, my eye caught a pale green insect just over half an inch long perched on a leaf.

The green mantidfly, Zeugomantispa minuta, looks like a cross between a green lacewing and a praying mantid. They live throughout much of eastern United States and are found in a variety of habitats from late June through early October.

With four clear wings folded rooflike over its body and a pair of grabbing forelegs held tightly against its long, slender thorax, this animal looked like a cross between a green lacewing and a praying mantid. In fact, it was the green mantidfly, Zeugomantispa minuta.

Mantidflies belong to the order Neuroptera and are only distantly related to mantids. Instead, they are related to antlions (whose larvae are known as doodlebugs), lacewings, and owlflies. Praying mantids are in the order Mantodea and are actually cousins of cockroaches.

Adult mantidflies capture and eat all kinds of small insects in captivity, but little is known of their food preferences in the wild. The larvae are also predators. Some are known to attack the pupae of moths, or the larvae of beetles, flies, bees, and wasps, while others prey on the eggs of spiders.

There are two basic strategies for mantidfly larvae to successfully dine on spider eggs; they are either egg sac penetrators or spider-boarders. Egg sac penetrators, such as those of green mantidflies, seek out their food directly.

When they find an egg sac they chew their way through the silk casing with highly modified jaws. The grooved mandibles and maxillae fit snugly together to form a pair of piercing/sucking tubes through which they draw out the embryonic fluids of the eggs.

Spider boarders are unable to chew their way inside spider egg sacs. Instead, they seek out a female spider, climb onto her body, and wait. What are they waiting for? Egg-laying day. The larvae disembark just in time to be wrapped up with the eggs in the egg sac.

Those mantidlfy larvae that initially hitched their fortunes to a male must eventually switch to the egg-producing sex. They switch hosts either while the male is mating or being cannibalized by a female.

The life cycle of mantidflies is a type of complete metamorphosis known as hypermetamorphosis. The first larval stage is quite active and resembles a slender, leggy silverfish, a body type that serves them well as they seek out egg sacs or spiders. Once inside the egg sac, the larva switch into feeding mode and go through two  grublike stages before completing their development into adulthood. These fat, short-legged larvae are decidedly more sedentary. Afterall, they are thorax deep in food and have no need to go anywhere.

One of the most amazing things to me about mantidfly natural history is that scientists figured it out at all. The seemingly unlikely relationship between mantidflies and spiders was first described in 1869 and, with careful and patient study, continues to unfold today. It is this unrelenting promise of discovery that keeps me and my colleagues forever enamored with the world of insects and spiders and dreaming of an endless summer.

© 2010, A.V. Evans

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