Archive for Insects & plants

TIPPING THE SCALES

Posted in Pests, Scale insects, Virginia with tags , , , , on September 19, 2010 by Dr. Art Evans

By Arthur V. Evans

Wax scales that is. Indian wax scales to be precise.

While trimming our nandina hedge this afternoon, I noticed a couple of small, white, barnacle-looking lumps on a stem. They were female Indian wax scales, Ceroplastes ceriferus (Fabricius). Sexing Indian wax scales is easy since males are not known in any wild population in Virginia. Adults are covered with a thick, white waxy layer that not only protects them from predators, parasitoids, and pesticides, but also helps them to survive freezing temperatures during the winter.

Reproduction is by parthenogenesis. One generation is produced annually in Virginia, but two or more appear in warmer climates. The first instars, or crawlers, hatch in spring and early summer and feed on leaves. They are not covered with a protective wax layer and are very susceptible to dehydration, parasites, and pesticides.

Adult Indian wax scales are conspicuous in late summer and early fall and suck sap from at least 122 plant species in 46 families. Prolific breeders, they quickly cover ornamental plants. Burgeoning wax scale populations not only ruin the plant’s appearance, but also cover them with sooty mold that develops on the prodigious amount of sticky waste (honeydew) that they produce.

Carefully tipping or lifting the scale to one side to detach the it from the plant stem reveals the orange and segmented body underneath. In the adjacent photo, the anterior of the body is on the lower right, while posterior is on the upper left. The mouthparts are visible and appear as a dark central spot at about the anterior third of the body.

Resource: Kosztarab, M. 1996. Scale Insects of Northeastern North America. Identification, Biology, and Distribution. Virginia Museum of Natural History, Special Publication No. 3. Martinsville, VA. 650 pp.

© 2010, A.V. Evans

SHARPSHOOTERS AND BROCHOSOMES

Posted in Leafhoppers, Parental care, Predators/parasites/parasitoids with tags , , , on September 17, 2010 by Dr. Art Evans

By Arthur V. Evans

Broad-headed sharpshooter, Oncometopia orbona.

Sharpshooters (Oncometopia species) measure 11-13 mm in length and are among the largest of North America’s leafhoppers. They feed on a wide variety of plants growing in gardens, parks, meadows, and woodland edges during summer and fall. Their sap feeding activities may spread plant pathogens. Females use their knifelike ovipositors to insert eggs into soft stems. The eggs are covered with a chalky substance (egg brochosomes) that make them more resistant to excess moisture and protect them from fungal infections and possibly attacks by parasitoids.

Broad-headed sharpshooter with brochosomes.

Brochosomes are intricately shaped proteinaceous particles that are produced by kidney-like structures called Malpighian tubules and excreted as a solution. After the sharpshooter molts, the solution is spread over the exoskeleton as a water-proof coating. Female sharpshooters store brochosomes as a single white dot on each forewing to be used later as a protective coating for their eggs.

© 2010, A.V. Evans

CAN YOU SAY OSMETERIUM?

Posted in Butterflies, Defense, Education with tags , , , , , , , on September 16, 2010 by Dr. Art Evans

By Arthur V. Evans

This summer a cadre of dedicated parents and volunteers joined forces at a nearby elementary school to create an outdoor classroom. The Holton Learning Project Garden includes a vegetable and butterfly garden that will introduce Holton Elementary School students, their families, and the residents of Belleview and beyond to the pleasures and benefits of urban gardening.

Compared to the dreary, sterile plantings of exotic trees, shrubs, and groundcovers found throughout much of the neighborhood, the vegetable and nascent butterfly garden has rapidly become a local hot spot for insects and spiders. As such, it provides an excellent site for macro photgraphy. Since August, I have endeavored to photograph as many of its multi-legged denizens as possible as part of an ongoing effort to document the arthropod diversity of my neighborhood in Richmond, Virginia.

While walking through the garden yesterday afternoon, I noticed several clumps of green spikes rising sadly from the straw-covered beds. I soon confirmed my initial suspicions as to the identity of the culprits that laid these once fat bunches of parsley to waste. At the very base of one of the clumps were two brightly banded larvae of the black swallowtail, Papilio polyxenes, polishing off the last few leaves.

When I knelt down to photograph the ravenous caterpillars, I accidentally brushed up against their food plant. Both caterpillars reacted immediately by assuming defensive postures. Bent over backwards, they spit up green fluid and produced a pair of long tentacles (osmeterium), that resembled bright orange horns. Soon my nostrils were filled with a strong, disagreeable odor that is best described as “spicy vomit.”

The osmeterium consists of two soft, finger-like tubes that are everted from inside the body through a slit in the prothorax just behind the head as a result of  increased blood pressure. This defensive gland is found in the caterpillars of swallowtail butterflies and is coated with highly noxious chemical compounds (2-methylbutyric acid and isobutyric acid) that deter predators, especially ants.

© 2010, A.V. Evans

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

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

CARPENTER BEES ARE BORING!

Posted in Ants, bees, wasps, Insects, Parental care, Pests with tags , , , , on April 1, 2010 by Dr. Art Evans

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

A BOUNTY OF BOXELDER BUGS

Posted in Insects, Pests, True bugs with tags , , , on March 24, 2010 by Dr. Art Evans

By Arthur V. Evans

A neighbor recently sought my advice about tiny, scarlet insects scurrying across his deck and up his walls, some of which were no larger than bits of coarsely ground pepper. Some had apparently found their way into his home and congregated in the well-lit windows on the south side of the house. A quick inspection of his home and property confirmed my suspicions; the tiny invaders were boxelder bugs.

For the past few weeks, I had noticed congregations of both adults and nymphs sunning themselves along back fences alleys and in trees growing along roadsides. I assured my neighbor that they posed no threat to property or pets, and that only in large numbers might they cause some damage to some plants.

The eastern boxelder bug, Boisea trivittata, is widespread throughout eastern United States. The wester boxelder bug, B. rubrolineata, is similar in appearance, but its found mainly west of the Rockies.

Adult boxelder bugs are flat, dark-gray insects with three red lines behind the head and may reach ½ inch in length. The thickened portions of their wings are bordered with red, while the membranous tips are blackish. They are strong fliers, flashing their bright red abdomens as they spread their wings and take to the air. Young nymphs are mostly red, but later stages appear darker as their wing pads grow larger. Both adults and nymphs have long, thin antennae.

Hibernating adults leave their winter hideaway with the advent of warm weather in late March or early April. Soon the females begin laying their dark reddish eggs in the crevices of bark on box elder trees and other nearby objects. The eggs hatch in two or three weeks, just as succulent new box elder leaves are beginning to appear. The nymphs eat and grow, shedding their external skeleton five times before becoming a fully winged adult. Up to two generations of boxelder bugs are produced annually.

Both adults and nymphs prefer to feed on the seed-bearing female box elder trees, sucking sap from the new leaves, tender twigs, and developing seeds. They will also attack ash, maple, plum, cherry, apple, and peach trees, as well as grapevines and strawberries. Damage from their feeding activities may cause blotchy yellow patches or brown spots on fruit and leaves. Severe infestations of boxelder bugs can result in misshapen leaves and fruit, but mature and healthy plants seldom suffer any serious harm.

In the late spring and early fall, flying or crawling boxelder bugs converge on stone piles, tree holes, and other protected places, sometimes by the hundreds. They may invade buildings, crowding into cracks and crevices in walls, door and window casings, and around foundations. They do not bite, nor do they damage buildings, furnishings, clothing, or food. However, they will soil curtains and walls with their waste and will definitely leave a stain if crushed.

The best way to keep unwanted boxelder bugs, as well as other insects and spiders, out of your home is by improving security. Replace screens and door sweeps. Repair thresholds and secure pet doors. Apply screens to vents and other openings. Caulk and seal all possible entry sites near doors, windows, crawl spaces, light fixtures, utility pipes or wires, weather boarding, and in areas along the foundation.

For boxelder bugs already in the house, vacuuming, sweeping, or picking them up are the most effective methods for dispatching them. They do not feed on household structures or reproduce indoors, so there is no need to use chemical controls inside the home. Aerosol sprays designed to kill ants and cockroaches are generally ineffective against boxelder bugs.

Removing leaf litter and other debris that serve as egg-laying sites near the base of female (seed-producing) box elder trees will reduce large populations of boxelder bugs outdoors. Eliminate other hiding places, such as piles of boards, rocks, leaves, grass, and other debris close to the house. Clear leaves and grass away from the house, especially on the south and west sides of the structure. Since boxelder bugs prefer to feed and lay their eggs on female box elder trees, plant male box elder trees instead. Male trees, propagated from cuttings taken from other male trees, are purchased from the nursery. These measures will significantly reduce the numbers of boxelder bugs looking to get inside your warm and cozy home.

As with many other insects labeled as “pests,” a little knowledge of their habits can help to reduce costly and sometimes unnecessary reliance upon pesticides, while at the same time raising our levels of tolerance and wonder. To me, this year’s appearance of boxelder bugs is just another marvelous pulse in the seasonal cycle of life. I am not the only one who feels this way. Just ask the folks in Minneota, Minnesota. They celebrate these little creatures each year with Boxelder Bug Days, a fall festival featuring bug races, bug poetry, plays, and other activities. If you can’t beat ‘em, join ‘em!

© 2010, A.V. Evans

INSECTS BRING OUT THE INNER CHILD

Posted in Beetles, Education, Grasshoppers & crickets, Insects, Musings, Virginia with tags , on March 18, 2010 by Dr. Art Evans

By Arthur V. Evans

Two wars, recession, earthquakes, and the seemingly endless wrangling of politicians—the news has not been very good lately. These combined with the usual everyday stuff makes it all too easy to get bogged down wondering where the world is headed. But occasionally, I am afforded a welcome change of perspective—that of seeing the world once again through the eyes of a child.

The author at the tender age of 14, or thereabouts, enjoying a summer day on a family camping trip somewhere in California's Sierra Nevada.

I was given this fresh viewpoint awhile back at the grand opening at the new Children’s Garden at the Lewis Ginter Botanical Garden in Richmond, Virginia. The garden is a microcosm of landscapes, plant adaptations, and human-plant interactions. A boardwalk accessible to all winds through various mini environments on its way to the Leafy Overlook and Tree House, introducing visitors to coniferous forests, deciduous woodlands, grasslands, and a butterfly meadow.

Also included is an International Village with Lilliputian playhouses depicting different cultures to demonstrate how people around the world use plants for food, materials, and medicine. As the garden matures, it will continue to be a haven for young naturalists and their families to explore plant diversity with its creeping vines, prickly plants, and inviting blooms, both sweet-smelling and otherwise.

It is also a great place for bug watching. That’s where I came in. I was invited to participate in the grand opening of the Children’s Garden as entomologist Dr. Art Evans, “the bug guy.” My task was to engage garden visitors in a series of bug talks and walks. My display was simple, consisting of a collection of local insects and a variety of popular identification guides for the region, as well as copies of my own magazine and newspaper writings on insects and spiders.

Families flocked around the display, amazed at the local insect diversity. Soon I was peppered with all kinds of questions. “Are they real?” “What is this?” “Does it bite?” “What does it do?” “What do they eat?” “Are they really found around here?”

Within just minutes, my world-weariness melted away. I was once again caught up in the excitement of my audience’s infectious enthusiasm for insects. After meeting with dozens of parents and their children, it dawned on me that there are two types people in this world: those that love insects and those that don’t yet know they love insects.

After answering some questions, I briefly introduced myself to the audience, and talked about some of the things that entomologists do in the world. Then we covered some bug basics, like their number of legs (6), body regions (3), and metamorphosis. Also discussed was how insects differ from other kinds of common garden animals such as spiders (8 legs, 2 body regions), worms (no segmented appendages), and slugs (no external skeleton or appendages).

The best part of the day was the bug walk. It was like going on safari. As we searched for tiny game, our goal was not to collect or kill, but to observe and marvel. The weather was overcast and decidedly cooler from the previous day when I had done my reconnoitering for bug hot spots at the garden. Still, there was plenty of insect hubbub about the flowering plants.

Bumblebees, soldier beetles, thread-wasted wasps, and various kinds of butterflies, skippers and moths clambered over the spikes of small yellow flowers as if they knew that fall had arrived and that warm and sunny days were now numbered. Both adults and youngsters peered into the blooms to admire the diversity and activity of this energetic, winged, and multi-legged assemblage. It was a great demonstration of how both plants and insects depend on one another for their very existence.

Nearby, black swallowtail caterpillars nibbled away on a lone fennel plant beneath the dining room window of the Bloemendaal house. We were all being treated to the fact that eating is job one for growing caterpillars of all stripes. Soon, they would all disappear as quickly as they appeared and transform twice more into entirely different creatures with no resemblance whatsoever to their current state.

The shrubs and low hedges were filled with the songs of amorous male crickets and meadow katydids, all scraping their wings together to produce characteristic chirps, clicks, and rasps to attract a mate.  In just a matter of yards we found more species of insects and spiders than could be found of mammals, birds, or reptiles in the entire garden!

This fabulous hands-on experience reminded me once again of why I got into this field in the first place. Sure, insects, spiders and their relatives are everywhere and are endlessly fascinating in their ways, fueling lifetimes of scientific research and popular writing projects. But I have come to understand that my attraction to all things insect is really about my desire to learn as much as possible of the world around me. I truly believe that the desire to learn is a very basic human need; the day we stop learning is the day we start dying.

To see the natural world through the eyes of children, or adults who have not lost their childlike sense of wonder and awe, is truly a gift. For me, it is a clear reminder of my own wonder and excitement that sparked my lifelong interest in insects nearly 50 years ago. I am confident in my knowledge that there are still plenty of insects and spiders out there to see, learn, and do for at least another 50 years.

The author, down and dirty on his knees at Virginia Beach in 2007, searching for false soldier beetles (Oedemeridae) under driftwood.

One of the great things about being a biologist is that we always get to keep a part of our childhood with us while we conduct fieldwork. It is part and parcel of our various job descriptions to wonder how things work as we get down and dirty on our hands and knees to rake through the soil, muck about in the mud, or slosh around in creeks and ponds. Now I ask you, what could be better than that?

© 2010, A.V. Evans

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