Stink Bug Season

October 3, 2011 under CANR News, Cooperative Extension

Pull up the welcome mat; they’re back. It’s early fall in Delaware, which means pumpkins on the vine, apples on the trees and stink bugs in the house.

“Last year, I got a flood of calls about stink bugs during the last week of September,” said Brian Kunkel, an entomologist with the University of Delaware’s Cooperative Extension. “Sure enough, this past week, Extension has been hearing from homeowners trying to get rid of stink bugs.”

“As the days grow shorter and the evening temperatures cooler, Delawareans are discovering these uninvited houseguests in their garages, porches and decks, as well as inside the house,” Kunkel said. “The brown marmorated stink bug becomes a nuisance pest when it heads inside to find overwintering sites.”

While merely an annoyance to most homeowners, the brown marmorated stink bug (BMSB) poses an economic threat to Delaware agriculture. Fruit crops seem to be at greatest risk, especially peaches and apples. About 18 percent of the mid-Atlantic apple crop had stink bug damage last year, according to the U.S. Apple Association.

“West Virginia apple orchards experienced significant crop loss last season because of the BMSB,” Kunkel said. “Here at UD, we’re doing everything we can to make sure that we don’t see the kind of crop loss that West Virginia had.”

Several of Kunkel’s colleagues in Extension and UD’s College of Agriculture and Nature Resources are researching BSMBs in soybean, lima bean, sweet corn, field corn and sweet pepper fields.

Two of the most active researchers are Joanne Whalen, the Extension’s integrated pest management specialist, and Bill Cissel, an Extension associate who is investigating stink bugs as part of his graduate studies.

Cissel and Whalen, assisted by two interns, are examining stink bugs in conditions similar to home yards and gardens, too. In UD’s Garden for the Community, a one-third-acre plot on the Newark campus, the duo surveyed stink bug nymphs, adults and egg masses on plants commonly grown in home gardens — tomatoes, zucchini, yellow squash, cucumbers, eggplant, sunflowers and bell peppers. Plus, they’re studying a plot of ornamental plants to see which plants stink bugs use as hosts.

Rutgers University, Virginia Tech, the University of Maryland and the Delaware Soybean Board are some of the partners on one or more of these projects.

Although Delaware has several native stink bugs, BMSBs originates in Asia and were accidentally introduced to the United States. First collected in Allentown, Pa., in 1998, BMSBs have been spreading across the eastern half of the U.S. ever since.

Kunkel said spiders and birds have been known to eat BMSBs (he’s heard reports of house cats eating them, too) but the pest has no recognized natural predator here.

The USDA Beneficial Insects Introduction Research Lab, housed on UD’s campus, is investigating biocontrol measures. Biocontrol introduces natural predators into an environment to control, if not eradicate, the pest problem. But the rigorous research process and government approvals needed for biocontrol measures can take years, even decades.

Delaware’s farmers are asking for help now. So the focus of Whalen and Cissel’s research is on monitoring to determine when to control stink bugs, as well as which insecticides provide the best control.

Field observations in 2010 indicated that stink bug infestations usually start on the perimeters of fields, Cissel noted. “We’re studying whether perimeter applications of insecticides will prevent stink bugs from penetrating the interior parts of soybean fields,” he said.

“In our corn research, we are trying to determine how much damage stink bugs are causing and when the plant is most sensitive to damage — is it when it’s silking, during grain fill or closer to harvest?”

Insect research projects typically run for two to three seasons, and most of the UD studies are in their first year. So it’s too early to discuss preliminary results, Cissel said, especially since the BMSBs weren’t as active this summer as previously.

“We had a really large outbreak last year,” Kunkel said, “but we’re not seeing those kinds of numbers this year.”

Tell that to Kathy Fichter, a resident of Chadds Ford, Pa.

“It’s just as bad as last year and it’s only the beginning of stink bug season here,” said Fichter, who always has a tissue at hand, ready to scoop up stink bugs. “My two sons won’t go near them, and these are boys who like bugs,” she said.

“Our neighborhood seems to be a ‘vacation destination’ for stink bugs. They come here by the hundreds, maybe even thousands,” she added. “My neighbors are in the same predicament. Yet, a few miles away, they aren’t such a nuisance.”

Kunkel isn’t surprised by Fichter’s stink bug woes, even though regional conditions are generally better. “Stink bug outbreaks — and insect outbreaks in general — tend to be localized,” he said. “We often hear of one neighborhood getting slammed while another neighborhood a half-mile away will have very few bugs.”

If the BMSB already has arrived at your house — or you want to make sure it doesn’t — take control measures now. The best thing you can do, Kunkel said, is to seal all cracks around windows, doors, siding, utility pipes and chimneys. Often overlooked, he said, are the cracks that can appear around dryer vents and gaps around window air-conditioning units.

“Try to look on the bright side,” Kunkel said. “Stink bugs that get inside are helping you to winterize your house. Wherever they got in today is where the cold winter winds will, later this year.”

Article by Margo McDonough

This post also appears on UDaily.

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Stink bugs shouldn’t pose problem until late summer

April 1, 2011 under CANR News, Cooperative Extension

Last fall, Stephanie Sturmfels battled stink bugs at her Pike Creek home and yard. “Stink bugs were on my deck, they were on my front porch, some were even in my house,” recalls the mother of two small children. “My four-year-old daughter, Madison, would go around and collect stink bugs in pieces of tissue.”

Now that spring has arrived, Sturmfels is worried that stink bugs may return in full force. So far, she has seen a few stink bugs but nothing like the invasion last September and October.

Brian Kunkel, a UD Cooperative Extension entomologist, has some good news for Sturmfels and anyone who despises the brown marmorated stink bug. “The adult stink bugs that were driving people crazy last fall will be giving birth this June and dying off soon afterwards. From now until then, they will be too busy feeding on plants in the landscape to spend much time around houses.”

“Their offspring — the nymphs — will spend most of the warm-weather months outside as they mature. They don’t feed in houses so you shouldn’t expect to see many on decks and patios or inside houses this summer,” adds Kunkel.

Best yet, nymph stink bugs can’t fly — they have wingbuds but not mature wings — so they can’t land in your hair, on your shoulders, or in a bowl of potato salad, the way those annoying adults were doing last autumn.

So rest easy and host a Memorial Day or Fourth of July cook-out, says Kunkel. You shouldn’t worry about scads of brown marmorated stink bugs crashing the party. However, when Labor Day rolls around, your guest list could unexpectedly rise.

“By late August, the nymphs have become adults and are able to fly,” says Kunkel. “What’s more, they start to congregate in houses, decks, garages and other warm spots during this time period. There is a lot that researchers don’t yet understand about the stink bug’s behavior but we do know that cooler temperatures at night motivate them to seek shelter.”

Twenty-six states now have populations of the non-native brown marmorated stink bug. If you have friends in other regions who shrug off stink bugs as a minor annoyance, you may have already guessed that Delaware has more of the critters than most places.

“This region is the epicenter of the stinkbug outbreak,” says Kunkel. Brown marmorated stink bug were first found in this country in Allentown, Pa. They arrived in 1998, as stowaways in packing crates from Asia, where they’re native. Here in the U.S., they have few natural predators. Some spiders, including arboreal spiders, feed on the brown marmorated stink bug.

“Don’t get rid of spiders in your yard and garden,” notes Kunkel. “Spiders are beneficial. In addition to stink bugs, they eat a wide variety of other pests.”

Keep in mind, though, that not all of Delaware’s stink bugs are bad guys; a native stink bug known as the spined soldier bug eats aphids and other pests. Delaware is home to three other native stink bugs: green, brown and dusty.

The brown marmorated stink bug has been more of a nuisance than a pest in the home landscape, thus far, but Delaware’s agricultural industry is monitoring the insect closely. This stink bug feeds on many plants, including lima beans and sweet corn, but is a particular threat to fruit-bearing trees.

“There are some orchards in other states that may go bankrupt this year because they had so much fruit damage from the brown marmorated stink bug last year,” says Kunkel.

He and other UD experts are launching several research projects aimed at protecting Delaware’s growers. One project will focus on when the stink bugs arrive in fields or at greenhouses, their life cycle, and the natural enemies (native parasitoids, predators) attacking this pest. Another project will evaluate the effectiveness of insecticides against the brown marmorated stink bug.

According to Kunkel, current insecticides provide little help in keeping this pest out of the house. Exclusion is the best approach. “Seal up every opening — caulk around windows, repair screens, install screens over your attic vents and replace any rotten wood on your house,” says Kunkel.

And take comfort in the fact that you won’t have stink bugs landing in your hair until later in the summer.

Article by Margo McDonough

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