Native Delaware: UD expert releases list of top five bad bugs of summer

May 7, 2013 under CANR News, Cooperative Extension

Summer is right around the corner and along with the good (long days, holiday weekends and lush, green landscapes) comes the bad (humidity, beach traffic and bugs).

Admittedly, there are plenty of beneficial insects that pollinate flowers or gobble pests, and plenty of insects that just hang around, doing neither bad nor good.

In fact, beneficial insects far outnumber pests, according to Brian Kunkel, an entomologist with University of Delaware Cooperative Extension. “More than 97 percent of arthropods typically seen in the home landscape are either beneficial or innocuous,” he says.

But it’s the other three percent that can drive us crazy, wreaking havoc with our prized rose bushes, tomato plants or elm trees. Or, in the case of biting insects, leaving itchy welts all over us.

Kunkel has pulled together a list of the worst pests – what he’s dubbed the “top five bad bugs of summer.”

“Another entomologist might come up with a very different ranking – pest conditions change from year to year and from location to location. I’ve had people call me about a stink bug outbreak in one neighborhood and the next neighborhood only had mild issues,” notes Kunkel. “But these ‘top five bad bugs’ are the ones that Extension gets the most calls about; the ones that inflict the most damage in area gardens, nurseries, and neighborhoods.”

Here’s Kunkel’s list of the top five bad bugs of summer 2013:

1. Scale pests

2. Wasps

3. Bagworms

4. Japanese beetles

5. Stink bugs

You might be wondering why cicadas didn’t top this list – after all, it’s been all over the news about the millions of cicadas ready to emerge in the Mid-Atlantic after a 17-year slumber.

While plenty of cicadas will be flying around southeastern Pennsylvania, southern New Jersey and Maryland this summer, Delaware will see only the occasional cicada crossing the state line. That’s because Delaware’s brood – called Brood X – is still burrowed under ground and isn’t due to emerge until 2021.

Bagworms are a pest in DelawareFar more worrisome than big, fat cicadas are teeny tiny scale pests, notes Kunkel. In fact, scale pest are the single biggest threat to Delaware home landscapes virtually every growing season, he says.

These insidious pests are easy to overlook because of their diminutive size and inconspicuous color. Oystershell scales are about one-eighth of an inch long and dark brown, blending right into the tree branches that they latch onto. It usually isn’t until the branch is dying that the homeowner realizes that these bumps are actually insects sucking sap from the tree.

While oystershell scales prefer certain trees – willows, lilacs, dogwoods and poplars here, as well as aspens and cotoneasters out West – they aren’t picky. They’ve been found on 130 different species of plants. And oystershell is just one of 8,000-plus different scale insects; almost every plant is vulnerable to some type of scale insect.

Kunkel rates wasps as the number two bad guy, not because of damage they do to the landscape but because of the damage they can do to people.

Only the female wasp stings but when she does, you’re going to know it. Even a normal, non-allergic reaction usually results in pain, swelling and redness around the sting site. A localized reaction can bring swelling to an entire limb. Allergic reactions, of course, require immediate medical attention.

Next up on the bad bug list are bagworms. Kunkel says there is variability from year to year in the size of Delaware’s bagworm population. “Some years are a lot worse than others,” he says.

Like scale pests, bagworms start out very small and aren’t likely to be noticed by the homeowner. They are generalists in their eating habits – they are known to eat about 100 different species of plants, including cherries, pines, junipers, arborvitae and birch.

Japanese beetles makes Kunkel’s list primarily because of Sussex County outbreaks in recent years “The population of Japanese beetles in Sussex is much higher than in Kent and New Castle counties,” says Kunkel. “Georgetown has some decent-sized populations but throughout Sussex they can be an issue.”

The last pest to make it onto the bad guy list – the stink bug – is the one everyone loves to hate. The brown marmorated stink bug made serious inroads into Delaware in 2011, particularly in New Castle County. Last summer, the population was considerably lower.

Farmers and homeowners in other states have seen considerable damage to their plants. Fruit orchards have been particularly hard hit.

“Thus far, brown marmorated stink bug has been more of a nuisance than a pest in the home landscape in Delaware,” says Kunkel. “However, some of our farmers have experienced issues. We have a number of UD research projects underway so we can work to control this pest.” 

Help for what’s bugging you

Got a pest problem in your yard or garden? Call Cooperative Extension’s free garden help line. In New Castle, call 831-8862; in Kent call 730-4000; in Sussex call 856-2585, ext. 535.

Article by Margo McDonough

Photo by Brian Kunkel

This article can also be viewed on UDaily.

Share

UD Cooperative Extension entomologist says summer insect populations uncertain

April 9, 2012 under Cooperative Extension

Recently, we’ve heard water cooler and dinner table pronouncements that it’s going to be a bad summer for mosquitoes, stink bugs and other insect pests. Prognosticators cite the mild winter and the fact that insects are out earlier this spring as their rationale.

Not so fast, says Brian Kunkel, University of Delaware Cooperative Extension entomologist. “The mild winter may not make much difference in the size of the insect populations this summer.  In terms of the early spring, yes, most insects are emerging or arriving about two weeks ahead of schedule,” he says. “But it’s too soon to say what impact — if any — this will have on insect populations later this season. There are many variables that could impact different species, either adversely or favorably.”

“Keep in mind, when I refer to insect populations I’m not just talking about pests,” he adds. “Beneficial insect populations — such as lady beetles — also are vulnerable to these variables.”

On the adverse side of things, some insects have become active sooner than their plant food source has become available. Various factors, not just air temperature, influence when plants bud. Photoperiod — the relative length of light and dark each day — is an important trigger for many plant species.

“We could see insect populations crash if their food source hasn’t bloomed or leafed out and they can’t obtain enough food,” says Kunkel.

Plant-eating insects that are host-specific — meaning they eat only one type of plant or from one plant family — are more vulnerable to such a crash.

Weather conditions during the rest of the season can be just as critical to many insect species as what already happened in winter and early spring.

“If the spring turns cool and damp, it could mean fewer insects in summer,” notes Kunkel. That’s because cooler, damper weather brings greater number of fungi that attack insects. A hot, dry summer could be even worse. Hot, dry conditions can make it difficult for some insects to survive.

Although Delawareans are tackling pesky insects earlier than usual, there is an upside. At the end of the season you’ll say goodbye to these pests that much sooner.

“The insects are going through their normal life spans, just earlier,” points out Kunkel. “For example, you may see Japanese beetles eating your roses earlier than normal this June. But, if that happens, then the beetles may peter out in August, instead of September.”

It’s anybody’s guess as to how bad insect pests will be this summer. But these tips, from Kunkel and the National Pest Management Association, are good advice in any season:

  • Trim back tree branches and other plants near the house.
  • Keep mulch at least 15 inches from your house’s foundation.
  • Get rid of standing water and other sources of moisture.
  • Make sure you don’t have holes in your screen windows and doors.
  • Seal cracks and small openings along the bottom of the house.
  • Tightly seal outdoor trash cans.
  • Learn about good bugs

Beneficial insects play an important role in the garden. Learn how beneficial insects can help manage your pest problems at this Master Gardener workshop to be held from 6-8 p.m., Wednesday, May 2, at the New Castle County Extension office in Newark. Cost is $15. Call 831-COOP to register and for more information.

Article by Margo McDonough

Photo by Danielle Quigley

This article can also be viewed on UDaily

Share

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.

Share

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

Share