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April 18, 1999

Battle Of The Bugs

Ladybugs recruited for "friendly attack" on white flies, aphids.

For The Dispatch/ Sunday News

ursery owner John Shelley says he's going a little buggy in his North Hopewell Township greenhouses this spring. And with good reason.

Shelley is bringing ladybugs, wasps and lacewings into his six greenhouses as part of a new integrated pest management program. The goal is to control the population of nursery pests, such as the whitefly and aphid, through the use of "friendly" insects.

Not widely practiced

While it's a practice many local garden centers and nurseries have heard of, few are making use of it, according to a survey of local centers.

"I know there are bugs out there, but we don't use them," said Sue Stebbins, a coordinator with Shiloh Nurseries, near Emigsville.

Likewise, at Miller's Garden Center near Red Lion, Hively Farm and Nursery near Dover and Stauffers of Kissel Hill East York location.

At Farmers Daughter Craft and Garden Center near Shrewsbury, the nursery actively "adopts" ladybugs that are brought in by irritated homeowners, releasing them into the greenhouse as a form of pest management. But the nursery/ garden center retailer does not have a systematic pest management plan that includes using the insects, said owner Megan Schaub.

"I know that we must have released close to a thousand (ladybugs last year)," Schaub said. "We just try to have them around here."

But after an infestation of aphid and whitefly in one of his greenhouses last year cost about $432 per week for chemical bombs and sprays, Shelley has decided to be more aggressive while using a more "natural" approach.

On guard all year: The problem he faced last year is that the chemicals only killed the adult insects and left the eggs unaffected. And because Shelley prefers not to use chemicals that eventually enter the soil and groundwater, an alternative army of "friendly" insects will hopefully address the problem at about one-fourth the cost and no environmental concerns.

Each insect has its own way of dealing with the greenhouse invaders.

Ladybugs eat the whitefly and aphids outright, then lay their own eggs for the next generation of eggs to hatch, having a ready reserve of ladybugs always waiting to hatch.

The wasp is not a conventional outdoor wasp as we might know it, but a microscopic Wasp that is about one-fiftieth of an inch long.

The wasps' and lacewings' eradication methods are almost something out of a science fiction horror movie, Shelley said.

Both strong predators, the insects lay their eggs in the chest cavity of the whitefly and aphid. The egg eventually erupts from the host body and kills it. "It's a unique way of doing it," Shelley said.

The downside is, however, that eventually the ladybugs, wasps and lacewings begin to kill each other.

So although Shelley maintains a "pristine" greenhouse, new shipments of ladybugs, wasps and lacewings must be periodically re-introduced through October.

What's on the menu:

Bee balm, phlox and monarda are particular favorites of the whitefly, Shelley said, while aphids favor the hibiscus. Their damage can wreck a nursery business.

"The leaves turn black and they get all sticky," Shelley said of a whitefly infestation. "Clouds of whitefly take to the air when a plant is touched." The standard treatment, in addition to the use of chemicals, is to cut back and inspect the plant leaves for a reinfestation. The plants are not fit to be sold until they have recovered and show new growth, he said.

"Once an infestation gets ahead of you, you've got trouble," he said.

A learning experience:

For those who want to know more about integrated pest management (IPM), Shelley plans to offer some information on his website at www.gdnctr.com.

After considering this years pest battles to be a learning experience, Shelley also hopes to hold workshops on pest management with insects for next year's outdoor gardeners. He's also considering the direct sale of insects at his facility.

"The big thing is going to be to try and change people's minds here in York County," Shelley said. The challenge is to turn growers minds away from the use of chemicals and in favor of the insects "they have killed all of their lives," he said.

Although he sells some environmentally friendly chemicals, including silica and diatomaceous earth, which kills beetles, Shelley says chemicals should be the "court of last resort" in the bug battle.

Test ranges:

He'll know if he's winning not only through the appearance of healthier plants, but through a series of sticky cards placed throughout the greenhouses.

Yellow cards attract the whitefly while blue ones attract aphids, Shelley said. A simple count of the number of insects caught on each card will show if the population is increasing or declining.

Next year, he'd also like to commission another great insect warrior to do battle by "transplanting" the nests of praying mantis to his greenhouse.


John Shelley's Garden Center & Nursery is located at 13579 Winterstown Road, also known as Route 24, just south of Winterstown.

It has been in operation since March 1991 and is owned by Springettsbury Township resident John Shelley, in partnership with his parents.

Located on 13.9 acres, with an additional six acres to be added this year, the nursery carries about 20,000 trees and shrubs, including one of the largest Japanese Maple tree collections in the United States. The nursery specializes in rare and unusual plants, including mini-conifers and mini-perennials.

It routinely draws customer from 5 states, with most regularly coming from Virginia, Maryland, Washington, DC, New Jersey, Ohio and much of Pennsylvania.

Outdoor pest management at the nursery is achieved with the aid of hundreds of birds Purple Martins, Killdeer, Robins, Baltimore Orioles, Blue Jays and Goldfinches who nest on the many trees on the site, Shelley said.

Hours of operation are 8am - 8pm, Monday through Saturday and noon through 5pm on Sunday.

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