Archive for the Winter Category

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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WINTER DARK FIREFLIES

Posted in Beetles, Defense, Insects, Virginia, Winter with tags , , , , , , , on March 15, 2010 by Dr. Art Evans

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

BIRDS, BUBBLES, BUGS: MY FIRST FIELD TRIP OF 2009

Posted in Beetles, Insects, Musings, Winter with tags , , on February 8, 2009 by Dr. Art Evans

Paul Bedell is a man of many talents. A double bassist for the Richmond Symphony, he is also a gifted naturalist. And he is a first-class birder, an indefatigable odonatololgist with a penchant for finding new state records and, as of late, Virginia’s leading authority on robber flies. Paul invited me to join him to today on a survey of rusty blackbirds for the Cornell Lab of Ornithology on a plot of land along the James River near Bremo Bluff in Fluvanna County. The temperature was supposed to surge up to a relatively balmy 60 °F, so I jumped at the opportunity.

Some beetles in eastern North America come out for only a few weeks or so in early spring. They are sometimes considered rare simply because many entomologists have yet to emerge from their own winter torpor in time to find them. I didn’t think that it had warmed up enough for a sufficient period of time to trigger beetle activity of any kind, but figured this would be a good opportunity to get my kit together for the upcoming field season.

There might be other insects out, too. For example, I might happen upon the first mourning cloaks and question marks of the season. These butterflies tuck themselves under bark and other protected places for the winter and are quickly spurred into action by the sudden appearance of a warm winter day. Maybe today would be one of those days when I would see them rocketing from one sunny patch to the next, or sipping nectar oozing from freeze-cracked maple trunks. Or not.

At 9 AM the sky was clear and the temperature had already passed 40 °F as we headed west on Highway 6 on the north side of the James River. We passed through the little towns with names like Manakin, Crozier, and Goochland. Just past Columbia, we turned left toward Bremo Bluff. Our final destination was a plantation called Glenarvon about an hour drive or so from Richmond. The beautiful home with its three columns and four chimneys was built in 1832 by William Galt Jr.

The origin of the name “Glenarvon” is uncertain. There is speculation that it was inspired by the title of a book by the same name penned in 1816 by Lady Caroline Lamb. This quasi-fictional gothic novel was inspired by the author’s four month-long affair with British poet Lord Byron. Or perhaps it was the name of Galt’s birthplace in Scotland. But I digress.

Upon our arrival, we were greeted by Glenarvon’s owner, Bill Winston. Knowing that I was an entomologist, Bill asked me if I knew what these large dark beetles were that he would find dead every now and again during the summer. I suggested a few possibilities, but nothing clicked with Bill. So, I suggested that he save the next one for me so I could identify it.

With a herd of curious cows looking on, Paul and I suited up with our birding, bugging, and photographic gear. We wandered down a narrow road into a ravine cut by a small creek as it flowed toward the James. The stands of trees mostly contained individuals with trunks no larger in diameter than the girth of my thigh. However, right along the creek’s edge stood several giant beeches. I imagined that the smooth, gray, and elephantine trunks of these trees were the legs of a small herd of long-necked sauropods that had come to drink. Again, I digress.

Finding one of these freshly downed trees of size with slightly loosened bark would be like hitting the mother lode. Many beetles and other wood-dwelling insects would find such a resource perfect for feeding, mating, and laying eggs. But I had no luck in finding such a tree. Instead, I contented myself with peeling back small patches of bark at the bases of several standing pine snags, none of which proved to be particularly productive.

I carried on down the road until it ended in a small field. Skirting the edge of this small opening was yet another small creek. I walked over to what looked like a mini-oxbow lake that was no more than three feet deep, 10 feet across, and about 25 feet long. Looking down from the bank, I could see right through the thin sheet of ice that covered the water down to the bottom of the creek.

In hopes of seeing some aquatic insect activity, I walked down to the water. As I approached the edge, a short series of marble-sized bubbles forced their way up from the depths of the submerged leaf pack. The rising spheres quivered like drops of quick silver as they rose up through the water column. Hitting the ice, these parcels of air were instantly pancaked and skittered along the ice, propelled by the current of the creek. No insects were in sight.

As I walked up the bank, a lone eastern boxelder bug flew past by and I watched it until it drifted out of sight. I thought that this colorful insect, pied with red and black, might prove to be the insect highlight of the day. But I was wrong.

Bill caught up with us later in the afternoon, plastic bag in hand. Inside was long dead female eastern Hercules beetle that he had found in the barn. A real beauty, she was. Bill said he had never seen a living one and wasn’t sure just how he would react if he ever did!

After investigating a few more fields and intervening woods, we decided to call it a day. Paul saw some good birds, but didn’t find his rusty blackbirds. But the relatively slow day failed to dampen our spirits. We both agreed that any day out in the field was a good day and began planning our next outing. Stay tuned.

©2009, A.V. Evans

 

 

WINTER STONEFLIES

Posted in Aquatic, Stoneflies, Winter with tags , , on February 4, 2009 by Dr. Art Evans

In Virginia, one of the very first insects to make an appearance in the New Year is the winter stonefly, Taeniopteryx. These flat, slender, and sprawling insects are grayish brown and measure 9.0 to 11.0 mm in length. They are also known by other appellations, such as willowflies and early black stoneflies.

Most of their lives are spent as larvae that nibble on aquatic vegetation and submerged debris as they crawl along coarsely pebbled and rocky bottoms of large streams and rivers. Beginning in late January or early February, the mature larvae leave their watery past behind for good and haul themselves up on nearby rocks and vegetation. The freshly emerged adults, having just escaped their larval exoskeletons, soon festoon boulders, logs, bridges, and nearby buildings by the dozens, even hundreds. They are most evident on warmer days, but are seldom noticed by passersby, save for naturalists on the lookout for signs of life after a long winter or anglers reading the latest hatch.

img_9991For me, the sudden appearance of these hardy insects serves as an annual reminder that winter is almost over and spring is on the way. This is welcome news to entomophiles living in the frosty and leafless eastern United States!

Many thanks to Boris Kondratieff of Colorado State University for helping me with the intricacies of winter stonefly identification.

©2009, A.V. Evans

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