UD entomologist discusses stoneflies, official state macroinvertebrate

June 25, 2013 under CANR News
stoneflies

Frank Peairs, Colorado State University, Bugwood.org

On a recent morning, Ingrid Feustel and Ed Trommelen donned rubber boots, grabbed nets and collection buckets, and splashed their way into a tributary of the Red Clay Creek in search of stoneflies.

The duo are spending the summer conducting a macroinvertebrate survey as Stream Watch interns for the Delaware Nature Society.

As Feustel set out sampling jars, Trommelen kicked up pebbles with the toe of his boot, then dragged the net over the churned-up water. “I’ve got some stoneflies,” said Trommelen, after a glance inside the net.

Most people would probably only notice leaves, twigs and pebbles but Trommelen quickly identified the stoneflies, even though they’re itty-bitty (one-half to 1 1/2 inches long as adults and even smaller as juveniles.)

The interns collected stoneflies throughout the morning, making note of how many were in each sample, as well as any other macroinvertebrates — such as mayflies, caddisflies and worms — that they found. While it’s certainly fun to splash around a sun-dappled creek on a June day, why would the Delaware Nature Society care how many stoneflies are in local creeks?

“Stoneflies serve as the canary in the coal mine in terms of assessing the water quality of streams and creeks,” said Brian Kunkel, an entomologist with University of Delaware Cooperative Extension. “It makes sense to focus on stoneflies. Stoneflies need running water that contains lots of oxygen. Scientists can tell if a stream is polluted or not based on whether stoneflies are present.”

In fact, the stonefly is such an excellent indicator of water quality that it was chosen to be the official state macroinvertebrate. The May 4, 2005, proclamation that made it official says that the designation of the stonefly was a means “whereby Delaware state government could recognize the importance of excellent water quality and the vital role played by healthy aquatic ecosystems in Delaware.”

Delaware actually has three official insects – the lady bug, the tiger swallowtail (which is the state butterfly) and the stonefly. The distinguishing feature of a macroinvertebrate is that it doesn’t have a backbone.

Stoneflies aren’t just an indicator of pure water; they also help to keep it that way. Most species are herbivores; they eat decaying vegetation and algae, said Kunkel.

There are 38 known species of stoneflies that call Delaware home. Nineteen live exclusively in the Piedmont, in the northern one-fourth of New Castle County; eight live in the Coastal Plain, which makes up the other three-fourths of the state; and 11 can be found in both the Piedmont and the Coastal Plain.

Adult stoneflies are weak fliers and like to hang out on stones (hence their name) and also on logs. If they lose their grip and fall into the water they may get eaten by trout, which prefer mayflies but will eat stoneflies if that’s the only food around.

Even if it doesn’t become dinner for a trout, an adult stonefly only lives about three to four weeks. Nymphs, on the other hand, which make their home in the water, can exist for one to three years in their immature state, says Kunkel.

Good places to search for stoneflies, says Kunkel, are the White Clay and Red Clay creeks in New Castle County, the Murderkill River in Kent County, and Woodenhawk, a tributary of the Marshyhope Creek, in Sussex County.

Delaware Nature Society has been conducting a Stream Watch program for 20-plus years, says Ginger North, the society’s associate director for natural resources conservation. During that time the Red Clay Creek has shown improvement in its water quality.

“Twenty years ago, the Red Clay was classified as a waterway that was severely impaired,” says North. “It only supported black fly larvae and other macroinvertebrates that can tolerate polluted water. But today, stoneflies can be found in the Red Clay’s tributaries.”

Article by Margo McDonough

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Master Gardener Native Plant Teaching Garden Open House Set for June 11

June 7, 2013 under CANR News, Cooperative Extension

J.W Wistermayer in the Master Gardeners Native Teaching GardenGardens are teeming with sights, sounds and tactile experiences. They’re meant to be used and enjoyed, not merely gazed at from a distance, says University of Delaware Master Gardener J.W. Wistermayer.

So, even though Wistermayer spends 5 to 10 hours a week tending to the New Castle County Master Gardener Native Plant Teaching Garden, he just chuckles when he sees that the garden’s plant identification tags have been rearranged.

“When tags are out of place, I know it means that kids are getting in here and discovering the garden,” says Wistermayer. “Our garden is next to the university’s Laboratory Preschool and Early Learning Center. At drop-off and pick-up times, kids and parents come look for new blooms, check to see if birds are in the bird boxes, and listen to the wind chimes. There is one particular path through three-foot-high plants that little kids love because they’re surrounded and hidden by all the foliage.”

The Native Plant Teaching Garden gets kids excited about plants and nature but its primary purpose is to promote the use of native plants in home landscapes, whether that landscape is several containers on a city apartment deck or an acre-plus in suburbia.

If you’re stumped about what to do with a spot where nothing grows, or how to jazz up a boring landscape bed, the Native Plant Teaching Garden is the place to go. Located on the grounds of the New Castle County Cooperative office in Newark, the garden features several distinct areas, including a butterfly garden, a rain garden, a meadow, a perennial border, and a foundation landscape planting.

The Master Gardeners also maintain a fruit and vegetable teaching garden, and a compost demonstration site, both of which are located behind the county office.

If you had to sum up the Native Plant Teaching Garden in one word, it would have to be “unexpected.” The garden features a fresh, exciting design that proves without a doubt that “native plant” isn’t synonymous with dull.

The foundation landscape bed, running the length of the county office, is a perfect example of this unexpected nature. While many of us select the same-old pink azaleas or red-blossomed dwarf cherries to line our homes, the Native Plant Teaching Garden’s foundation planting is full of unexpected textures, colors and plant choices. Such as the feathery foliage and steel blue flowers of threadleaf bluestar. Or the brushy blooms of fothergilla, which will sport fiery foliage in fall. There’s nothing formal or structured about either of these native species, yet they work well in this foundation planting.

Another unexpected touch is the green roof on top of the garden arbor. Covered with vegetation, this green roof absorbs water and creates habitat for wildlife. If it was used on a home or business, its insulating effects could lower cooling and heating costs, too.

One of Wistermayer’s favorite spots in the garden is a wooden bench positioned under a river birch. From there, he can hear wind chimes that hang in a nearby maple. Wistermayer often stops by the garden on Sunday to water the plants and ends his work session with a bit of quiet time relaxing on the bench.

The Master Gardeners will be hosting an Open House at the Native Plant Teaching Garden on June 11 from 6 p.m. to 8 p.m. They’ll be joined by Brian Kunkel, an entomologist with UD Cooperative Extension, and Carrie Murphy, horticulture agent for New Castle County Extension. The Open House is free but pre-registration is necessary. Email Murphy at cjmurphy@udel.edu.

Article by Margo McDonough

Photo by Danielle Quigley

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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.

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Spring means lush blooms and wide variety of beneficial bugs

March 20, 2013 under CANR News, Cooperative Extension

assassin bugSpring officially gets underway March 20, bringing blooms, birds and bugs. Lots of people get excited about the first redbud flower or returning tree swallow. Fewer get enthused about the first Eastern tent caterpillar or green lacewing that emerges in spring.

But a wide variety of flowering plants and songbirds wouldn’t exist without insects. “A number of different insects pollinate plants and many are an important protein source for birds,” notes Brian Kunkel, an entomologist with University of Delaware Cooperative Extension.

Bugs get a bad rap, says Kunkel. Some bugs – stink bugs, Japanese beetles and yes, Eastern tent caterpillars — deserve the nasty reputation because they damage or destroy ornamental plants, turf grass or agricultural crops.

But many insect species are innocuous – they do no harm. And plenty more, like immature green lacewings, are good guys.

While the adult form of this insect eats pollen and nectar, the young green lacewing gobbles up a slew of pests, including white flies, aphids, adult mealy bugs, and mealy bug eggs and larvae.

“Beneficial insects far outnumber the pests,” says Kunkel. “In fact, more than 97 percent of arthropods typically seen in the home landscape are either beneficial or innocuous.”

(Arthropods, as you may recall from your school days, include not only insects but also spiders, predatory mites and other creepy crawlies.)

Gardeners often grab a can of pesticide at the first sight of a bug, without even bothering to figure out whether the species is a pest.  Retired Hercules technologist and current Master Gardener Frank Ebright used to do that, too.

“I spent my career working with chemicals. I have nothing against them; chemicals have helped to save lives. But I don’t see a need for them in my garden,” says Ebright.

He tends to a two-acre yard in Cecil County, Md. Once he became a Master Gardener 19 years ago, Ebright’s use of chemical pesticides declined but he still spot-treated roses and other plants with pest problems. About five years ago he abandoned lawn chemicals for good and reports that his landscape has never looked better.

“Once I got rid of the chemicals, the beneficial insects starting coming to my yard and taking care of my pest problems,” he says.

Ebright will be leading a Master Gardener workshop about beneficial insects and integrated pest management on May 16. “I want gardeners to use chemical control as a last resort, not the first defense, and learn who their friends are.”

Sometimes it’s easy to identify your friends. Even though there are some 150 species of lady beetles in the U.S., these beneficials are a cinch to recognize. Their size and color may vary but all sport characteristic spots on their abdomens.

Other times, it’s tough to tell friend from foe. For example, the hover fly looks like a stinging hornet but the adult form is a first-rate pollinator that has been ranked just after the honeybee in its effectiveness. Plus, the larvae of many species of hover flies gorge on aphids, a pest that can wreak havoc on everything from roses to maple trees.

Ebright’s go-to book for identifying insects is Garden Insects of North America by Whitney Cranshaw. If he sees an unknown bug, he snaps a photo of it then compares it to images in Cranshaw’s book.

One of the first steps in integrated pest management is “making sure your plants are happy,” says Kunkel. Essentially, that comes down to “planting the right plant in the right place,” he notes.

If a plant requires moist soil, don’t put it in a dry spot. If it needs full sun, don’t think you can get away with partial shade. A stressed plant won’t be happy and can be more vulnerable to pest infestations, says Kunkel.

Companion plants are another element of integrated pest management. Nasturtium is commonly used as a companion plant, especially in vegetable gardens. Plant nasturtium near cabbage, tomatoes, cucumbers, broccoli, collards and kale. The aroma of this colorful annual will repel aphids, squash bugs and striped pumpkin beetles.

Presentations

• May 16, 6-8 p.m.: Find out how to use integrated pest management for an attractive yard and productive vegetable garden. New Castle County Cooperative Extension Office, Newark. $25. To request a registration form, call 302-831-COOP or download the form online.

• June 11, 6-8 p.m.: Join Brian Kunkel and other experts for a plant, pest and beneficial insect walk. New Castle County Cooperative Extension Office, Newark. Free. Register by email to cjmurphy@udel.edu.

Article by Margo McDonough

Photo courtesy of Brian Kunkel

This article can also be viewed on UDaily.

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UD Extension Scholars involved in range of projects this summer

August 15, 2012 under CANR News, Cooperative Extension

Ask Donald Seifrit, Jr., what he does as a University of Delaware Extension Scholar and he hesitates before answering. It isn’t easy to sum up all the tasks he has taken on during this summer-long internship program.

Under the direction of Carrie Murphy, a horticulture agent in the New Castle County Extension office, he might start his morning by identifying fungus on a cherry branch or insect holes on a tomato leaf. He’ll then contact the gardener who dropped off the plant or insect sample and suggest solutions to the problem.

In the afternoon, he may head to a UD greenhouse where he’s working on three different research projects with Richard Taylor, an Extension agronomy specialist. Seifrit has been busy evenings and weekends, too, at events ranging from a farmers’ field meeting in Middletown to preparing for a community garden workshop in the Southbridge section of Wilmington.

The Extension Scholar program gives students and recent grads the opportunity to gain real-world experience as interns with UD Cooperative Extension.

Jan Seitz, former associate dean of the College of Agriculture and Natural Resources and director of UD Cooperative Extension, created the program, which is supported by an endowment fund established by Dover growers Chet and Sally Dickerson.

“I’d like to work in industry, initially, but I also think it could be rewarding to get my teaching certification and be a high school agriculture or biology teacher,” says Seifrit, who graduated in June with a plant science degree. “The Extension Scholar program is giving me a taste of careers in which I could use my plant science degree.”

Andy Kness is another Extension Scholar with a new plant science degree from UD. Kness knows he wants to be a researcher and will be back in the classroom in September, pursuing a master’s degree in plant science. In the meantime, he’s working with Cooperative Extension entomologist Brian Kunkel.

One valuable lesson Kness has already learned is that research doesn’t always go smoothly. Take, for example, a stink bug project that he and Kunkel had planned to tackle this summer.

“It’s a dud; there’s nothing to talk about right now,” says Kunkel. That’s because the brown marmorated stink bug – that nonnative stink bug that has caused crop loss and landscape damage in Delaware – is in remarkably short supply this summer.

That’s good news for homeowners and farmers, not so good if you’re trying to evaluate the effectiveness of insecticides against the stink bug as well as the natural enemies that attack this pest. Kunkel and other UD researchers want to be able to present solutions when the stink bug does make its inevitable return.

One recent morning, a few forlorn stink bugs munched leaves in a rearing container while Kunkel and Kness focused their attention on the insect that has kept them busy this summer – red-headed flea beetles.

“These critters chew holes in plants and can cause significant destruction to nursery plants,” says Kness. “It’s not really a problem for homeowners as much as it for nurserymen. They can’t sell plants with flea beetle damage even though these plants aren’t really damaged and will look fine in their second season.”

Kness is assisting Kunkel with a project that could provide an environmentally sustainable way to control this beetle. The answer may lie in a tiny white worm, more formally known as entomopathogenic nematode. This parasitic worm attacks the larvae of the red-headed flea beetle by releasing bacteria that eventually kills it.

Two weeks ago, Kness introduced these worms into petri dishes filled with red-headed flea beetles to evaluate their usefulness. Next up, he and Kunkel will replicate the experiment in greenhouse plants and then out in the field.

Six students were named Extension Scholars this summer. The other interns have been working with military youth at Dover Air Force Base, developing State Fair programs, teaching 4-H equine camps and assisting with honey production at the UD apiary.

“I wish there had been something like this program when I was in school,” says Murphy. “I think it’s a fantastic way for students to learn job skills while gaining an understanding of the role that Extension plays in the community and the wide range of things that we do.”

Article by Margo McDonough

Photo by Danielle Quigley

This article can also be viewed on UDaily.

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Butterfly season only average, according to UD entomologist and others

July 17, 2012 under CANR News, Cooperative Extension

Brian Kunkel’s weekend strolls at Middle Run Natural Area make him see red – not because he’s angry but because the red admiral butterfly has been abundant at this 850-acre park east of Newark. A large, red-banded butterfly, the red admiral has been seen in large numbers throughout Delaware this summer.

“The red admiral is experiencing an irruption – a rapid and irregular increase in population numbers,” says Kunkel, an entomologist with UD Cooperative Extension. “It’s not just here in Delaware; this irruption also has been reported in New Jersey, the Poconos, western New York and other Northeastern locales. The last time a red admiral irruption was seen locally was 2001.”

The red admiral is the bright spot for Delaware butterfly watchers this summer. All in all, it’s shaping up to be just a so-so season for butterflies.

“Butterfly numbers were good at the end of May and into June but then things really backed down,” says Sheila Vincent, a group program coordinator for the Delaware Nature Society who maintains Ashland Nature Center’s Butterfly House.

“Mid-July to mid-August is typically the peak of butterfly activity in Delaware but we’ve seen fewer individuals flying,” says Vincent, “Right now, I don’t think we’re going see a repeat of 2011 and 2010, both of which were very good years for butterflies.”

Butterfly populations are influenced by a complex interplay of temperature, moisture and food supply. Different species are impacted by different factors. For example, a species that overwinters in the adult form – such as the mourning cloak — will have better survival rates in milder winters, says Kunkel. If the butterfly’s host plant flourishes during a rainy spring, odds are that butterfly will do well that season, too.

“With so many factors influencing population density, I can’t begin to speculate on why overall butterfly numbers appear lower this year,” says Kunkel.

Delaware has about 120 species of resident breeding butterflies. Considering that most states have about 100 species, Delaware is a pretty good spot for butterfly watching.

“Delaware is home to both the Piedmont Plateau, in the north, and the Coastal Plain, in the middle and southern parts of the state. This makes for a greater diversity of butterflies,” says Vincent. “For example, we don’t get cloudless sulphur butterflies in the Piedmont but on occasion you see a straggler cloudless sulphur fly up from the Coastal Plain.”

If you want to attract butterflies to your yard, Kunkel has two important tips. “First, get lots of plants that caterpillars like,” he says. “Gardeners tend to focus on nectar plants that provide adult butterflies with energy but you also need plenty of food sources for caterpillars – the next generation of butterflies.”

Most caterpillars eat only one specific plant or from one plant family. Do your research. If you love the great spangled fritillary butterfly, plant violets, the food source for this butterfly’s caterpillar. If it’s Eastern tiger swallowtails that you’re trying to attract, plant tulip poplar, sweetbay magnolia and black cherry trees.

If you’ve always prided yourself on a flawless, neat-as-a-pin garden, you may not like Kunkel’s second piece of advice – “tolerate insect feeding.”

Caterpillars eat the leaves and stems of plants, which mean, of course, little holes on the leaves of your plants. “If you want to enjoy the sight of the pipevine swallowtail butterfly, with its brilliant blue wings, you’ll have to accept that your pipevine plants are going to get chewed up a bit by this butterfly’s caterpillars,” says Kunkel.

At the University of Delaware Botanic Gardens, feeding the caterpillars is seen as just as important as feeding the butterflies. The gardens’ Lepidoptera Trail, which opened in 2009, features a wide range of plants to attract caterpillars.

“The trail is not a butterfly garden, which is designed to attract butterflies to feed on nectar,” says garden director John Frett. “It is an ecosystem to attract Lepidoptera throughout their life cycle. It’s a place for them to lay their eggs, which become larvae or caterpillars before entering the inactive pupal stage and then emerging as butterflies, moths or skippers.”

Besides, caterpillars are cool in their own right. “Take the caterpillar of the spicebush swallowtail butterfly. It looks like something out of a cartoon,” marvels Kunkel.

This caterpillar features oversized fake eyes on its thorax and is a garish neon green color at certain stages of development. The fake eyes and bright color is supposed to make the caterpillar look like a snake and thus scare away birds and other predators.

The Lepidoptera Trail, as well as the rest of the UD Botanic Gardens, is open daily from sunrise to sunset for free self-guided trails. For more info, go to http://ag.udel.edu/udbg or call 302-831-0153.

Article by Margo McDonough

Photo by Brian Kunkel

This article can also be viewed on UDaily.

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Central Delaware residents find biting flies peskier than usual this season

June 13, 2012 under Cooperative Extension

Have you had more unwanted guests at your backyard barbecues this year?

Other Delawareans are sharing your pain.

We’re not talking about that pesky, loquacious neighbor or the cousin who stays long after everyone has left, we’re referring to biting flies ruining your good times.

“This is shaping up to be a bad season for flies,” says Brian Kunkel, an entomologist with University of Delaware Cooperative Extension. “Most of the calls I’ve received from the public this spring have been about biting flies.”

At Greg Mannering’s home in Bear, the flies have been bothersome. “I noticed deer flies early; they’re worst in shady areas,” says Mannering.

Unfortunately, Mannering resides in one of the buggiest parts of the state – this season, anyway. “Middletown seems to be the worst area for flies but the entire central portion of the state – Bear to Smyrna — has been impacted,” notes Kunkel. “It’s the same way with stink bugs and other pests — outbreaks often are localized.”

Beyond that, Bear and Middletown feature a good amount of the habitat that deer fly need to survive — marshes and wetlands. While adult deer flies can live in a variety of places, as long as water is nearby, deer fly larvae appear to be limited to aquatic habitats, including marshes, ponds and streams.

But even if you don’t live near a marsh, chances are you’ve got plenty of flies keeping you company. In the U.S., there are about 16,000 species of flies. However, compared to other countries, Americans get off easy — worldwide, an estimated 145,000 species exist. Only the polar ice caps are devoid of flies.

Entomologists call this order of insects Diptera but most people know them as flies, gnats, maggots, midges, mosquitoes, keds, bots and various other names. Whatever you call them, they’re frequently annoying, often costly, and sometimes downright dangerous.

Flies are expensive and not just because of all those citronella candles you buy before barbecues. Flies contaminate or destroy $10 billion worth of agricultural products annually in the U.S., according to the U.S. Department of Agriculture.

In Delaware, the two flies that farmers worry about most are seed corn maggot and Hessian fly, according to Joanne Whalen, the integrated pest management specialist for UD Cooperative Extension. Seed corn maggot is a slender, light gray fly that feeds not only on corn but on soybean and many vegetable crops.

“Seed corn maggot was a major pest of peas this spring,” reports Whalen.

The larval stage of Hessian fly can be an issue in wheat and was a problem a number of years ago. In recent seasons, this fly hasn’t caused much damage to Delaware crops, says Whalen.

As for the danger flies hold, consider that more than 100 pathogens are associated with the common house fly, including Salmonella, Staphylococcus, E. coli and Shigella. Flies are efficient at spreading disease because they move quickly from things like rotting garbage to landing on your picnic lunch (without washing their feet off in-between).

But many species of flies don’t transmit disease and, in fact, actually serve a beneficial function. The hoverfly, which looks like a small bee, eats aphids and other pests.  And a species known as the long-legged fly gobbles up mosquitoes.

“Not all flies are bad,” notes Kunkel. “Some are pests, some are beneficial and some are categorized as incidental — they neither injure nor aid us.”

To keep the bad guy flies away from your outdoor events, Kunkel suggests several control measures.

Research has shown that citronella and other essential oils are effective natural fly repellants. So stock up on citronella candles; they really do work, says Kunkel.

Mannering also uses natural methods to combat deer flies at his Bear home. “What I do is grab an herb like rosemary or thyme in my garden or some marigolds and rub my hands to help repel the flies and mosquitoes,” he says.

Kunkel has heard good things from Extension colleagues about some of the new personal bug zappers. These appliances are meant to be clipped to a belt loop or worn in a holster.

What doesn’t work well, says the UD entomologist, is DEET and other chemical measures.

“It’s cost-prohibitive to spray your yard with DEET and not very effective, either,” notes Kunkel. “It also can present environmental concerns. Plus, I think many people are uncomfortable with the idea of spraying themselves and their kids with DEET every time they go outside.”

Learn more

Got a fly question that’s bugging you? Meet Brian Kunkel and other UD Extension experts at the June 20 open house at the Native Teaching Garden at the New Castle County Extension office in Newark. Master Gardeners are sponsoring this event, which is free and runs from 6 p.m. to 8 p.m. Call 831-COOP for more info.

Article by Margo McDonough

Photo by Danielle Quigley

This article can also be viewed on UDaily.

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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

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Native Delaware: Beneficial Spiders

October 27, 2011 under CANR News, Cooperative Extension

A big, furry, fake spider, dangling over a doorway or front porch, should produce a few screams from unsuspecting trick-or-treaters — before they dissolve in giggles when they discover that this particular arachnid is made of plastic.

As for real spiders, people don’t have much to fear, especially here in Delaware, according to Brian Kunkel, an entomologist with University of Delaware Cooperative Extension.

Most large, hairy, and scary-looking spiders, such as the wolf spider, will hurt a fly but they won’t hurt you.

“Delaware’s native spiders are more friend than foe,” says Kunkel.  “Only one poisonous spider is found in Delaware, the black widow. Of course, for those who are allergic, any spider bite can be a problem.”

Spiders are considered beneficial because they keep insect populations in check. Insects and spiders are both classified as arthropods but insects have three body parts and six legs, while spiders have two body parts and eight legs. In addition, spiders have two hand-like appendages called pedipals that they use to hold food. The pedipals contain sensory organs that allow spiders to taste their food. These sensory organs also are found on the spider’s legs.

The majority of spiders have eight eyes but despite all those eyes most spiders have bad vision, says Kunkel.  An exception is the jumping spider, which relies on its keen eyesight to locate its next meal. After spotting its prey, this spider takes a flying leap and, if successful, lands right on top of it. The wolf spider also captures its prey by hunting and chasing it down, though it’s more a sprinter than a jumper.

Another group of spiders captures its prey by using the ambush method – they just hang out, motionless, until a tasty little insect comes along into easy grasping range.

Constructing a web is the most common method that spiders use to capture prey. Web spinners in Delaware include the orb weaver, comb-footed, sheet web and funnel web spiders.

When it comes to dining habits, spiders are generalists, meaning they’re a lot like the guy at the smorgasbord sampling one of everything. In contrast, the monarch butterfly caterpillar is a specialist because it eats milkweed and only milkweed. If you want to attract spiders to your yard – so they’ll gobble up all the bad bugs – plant a variety of plants and plant types, says Kunkel. Use as little pesticide as possible; it can kill spiders as well as the pest insects.

“Spiders are a sign of a healthy garden,” says Kunkel. “They are often the most important biological control of pests in the home landscape as well as on cropland. In addition, spiders are a good source of food for birds and small mammals, particularly in winter and spring.”

Doug Tallamy, chair of UD’s Department of Entomology and Wildlife Ecology, can personally attest to the role of spiders in controlling pests. The first summer he lived in his house it was overrun with flies, thanks in part to a nearby horse barn.

Then Tallamy and his wife began transforming their barren yard. “When we moved in, the yard supported little more than mustard grass and ragweed,” he says.

After he planted a wide variety of native trees and plants, the wildlife came – everything from bluebirds to spiders.

“One predator, in particular, that I saw pouncing on the flies is a species of jumping spider,” says Tallamy. “These small but powerful spiders learned that our windows are great hunting grounds for flies.”

Because our trees and shrubs have grown since that first summer, the jumping spider now has plenty of places to hide and lay its eggs. And our native plantings provide an alternative food source, as well.”

So go ahead and scare someone with a fake spider this Halloween – just don’t scare off the real, beneficial spiders in your yard and garden.

Article by Margo McDonough

Photo by Evan Krape

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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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