Archive for True bugs

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

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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

WHAT’S IN YOUR ATTIC? BROWN MARMORATED STINK BUGS, PERHAPS

Posted in Environment, Insects, Pests, True bugs, Winter with tags , , , , , on March 15, 2010 by Dr. Art Evans

By Arthur V. Evans

Last month, while attending a meeting of the Bull Run Mountains Conservancy held in The Plains, Virginia, I was approached by several members who wanted to know about a stink bug that had invaded their homes by the dozens or hundreds in the fall. At first I thought they were referring to a species of bark stink bug, Brochymena, which sometimes enters homes by hiding under the bark of firewood hauled inside for the fireplace. Just as I was going into my spiel about sending me a photograph or a specimen for identification, someone said, “Look! There’s one!”

 

The brown marmorated stink bug, Halymorpha halys Stål, is steadily expanding its range across North America.

 

Sure enough, a robust gray stink bug was slowly making its way up the wall toward a window through which the day’s last rays of sunlight were shining. Judging from its distinctive markings, I knew that it was not a species of Brochymena and wondered if it might be the brown marmorated stink bug (BMSB), Halymorpha halys Stål. My suspicions were soon confirmed.

This uninvited insect from Asia has proven to be quite a nuisance to many homeowners in northeastern United States for the past several winters. They are much more likely to take up residence inside buildings than either of their native look-alikes, Brochymena and Euschistus.

BMSB was first reported from Allentown, Pennsylvania in 2001, but it turns out that the species has been in that area since at least 1996. The very first individuals probably arrived in America as stowaways, possibly as eggs, on packing crates most likely shipped from China or Japan. Since then, they have spread throughout Connecticut, Maryland, New Jersey, New York, Pennsylvania, Virginia, and West Virginia. As of 2004, an isolated population has become established in Oregon.

Like other stink bugs in the family Pentatomidae, BMSB are “shield-shaped” in outline. They are about 17 mm in length and are nearly as wide as they are long. Unlike similar species of native stink bugs, BMSB has white bands on the antennae and dark bands along the edges of the abdomen surrounding the wings. The head and pronotum (upper surface of the mid section, or first thoracic segment) have patches of small, round coppery or metallic bluish pits. The glands that put the stink in these and other pentatomids are located on the underside of the thorax and upper surface of the abdomen.

 

A nymph of the brown marmorated stink bug, Halyomorpha halys.

 

Brown marmorated stink bugs probably produce a single generation per year in America, but records from the sub-tropical regions of China indicate that there are 4-6 generations annually. Local populations of adults emerge from their winter hideaways in early June and begin mating and laying eggs almost immediately. The small black and red larvae (nymphs) soon hatch and molt five times during the months of July and August. Adults appear in mid August and begin seeking overwintering sites by mid September as the evenings start to become cooler.

To escape the cold, BMSB enter homes, out buildings, office buildings, and other structures by crawling under siding and shingles, around door and window frames, and into crawl spaces and attics. Once inside, they will settle in and become inactive for short periods. However, reinvigorated by the warmth of home heating systems, they are driven to crawl over walls and furniture, or fly clumsily to lights and windows.

As they bumble about, BMSB leave their odor on everything they land and crawl on. The accumulation of this odor at a good hibernation site serves as a powerful chemical beacon that attracts their brethren to the same location year after year.

The best way to keep BMSB out of homes and other structures requires preventative measures to be taken during the summer, after the bugs have already left, to prevent a re-infestation in the fall. Seal cracks and spaces around doors, windows, vents, utility access points, siding, trim, fascia boards, and chimneys. Caulk is handy for small cracks, but wire mesh and screens may be required when dealing with larger spaces associated with attics and foundation vents.

The good news is that once inside your home, BMSB will not bite you or your pets, spread disease, nor lay their eggs. Their piercing-sucking mouthparts are adapted for drawing sap from plants, not damaging furniture, clothing, or other household items.

Using insecticides on BMSB indoors is not particularly effective. Crushing them or sucking them up with a vacuum cleaner causes them to release their noxious odors that may persist in a room or on cleaning implements for sometime. Any disturbance perceived by the bugs as a threat will cause them to stink as a defensive measure. The best thing to do is to simply let them walk on a piece of paper and take them directly outside.

What is being done about BMSB nuisance in America? Since they have yet to become serious agricultural pests here in the States, there is little incentive for chemical companies to develop pesticides to combat them. Pesticides of any kind are incredibly expensive to bring to market and the number of homeowners plagued by home invasions of these bugs will never support the company’s efforts to recoup their investment, much less generate a profit.

But all is not lost. Researchers are learning everything they can about BMSB so that they can identify the weak links in their life cycle and exploit them to affect some level of control. Select BMSB genes and proteins are being sought for the possible development of genetically modified crops that will help suppress their numbers. There is also the possibility of using parasitic insects that will attack stink bugs during egg stage, not only to lessen their potentially harmful impact on crops such as soybeans, cotton, and corn, but also to reduce the numbers of individuals seeking shelter for the winter.

One of the more promising avenues of research involves the synthesis of attractant chemicals, or pheromones, to use in stink bug traps. Although BMSB attractant pheromone is currently unknown, scientists have discovered that they are attracted to the pheromones produced by the male of another species of stink bug native to Japan, Plautia stali Scott. Traps in America baited with this pheromone not only attract BMSB, but also some native species of stink bugs and a tachinid fly, Trichopodes pennipes,  that parasitizes native stink bugs.

Why would these stink bugs and one of their natural enemies be attracted to the pheromone of another species of stink bug? Research on other stink bugs species suggests that some use the pheromones of stink bug species other than their own in an effort to locate better feeding sites. Further, this chemically induced aggregation of different species of stink bugs may serve as a defensive strategy known as the “selfish-herd effect.” As the herd, or aggregation, grows individual stink bugs are increasingly less likely to be selected by a parasitic fly that, not so coincidentally, uses the very same pheromone to locate its victims. The discovery of the attractiveness of this pheromone offers up a potentially useful tool for monitoring and managing BMSB in America.

BMSB is steadily expanding its range across North America. Although clearly annoying to homeowners, the degree to which this species will become an agricultural pest in America remains unclear, especially as it moves south into warmer climates. Within their native range of China, Japan, Korea and Taiwan BMSB is most certainly an agricultural pest, attacking soybeans, apples, peaches, figs, mulberries, citrus, persimmons, and a variety of ornamental plants.

For now, all we can do is batten down the hatches and hope that science will come to the rescue.

© 2010, A.V. Evans

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