Japanese beetle invasion fought Study seeks to curb pests in Winterport

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Score after score rises from the earth, their numbers equaled only by the knobby mounds left in the turf as they metamorphose.

An army of invaders intent on destruction, they wing their way to vulnerable targets by the hundreds, swarming over their prey, devouring it from the top down and leaving the skeletonized remains to wither and die in the scorching summer sun.

As they cut their ruinous swath, they mate and lay eggs – up to 60 per female – assuring their resurrection for another year.

Many have tried to stop them. All have failed. And so, unchecked since their arrival in the East nearly 100 years ago, the invaders marched on, north, south and west.

Until one day they descended on a town called Winterport, which welcomed them with acres of manicured turf and a steady supply of food.

Then Pam Tremblay moved in.

Unaware of what was lurking in the neighborhood, Tremblay came face to face with the enemy last summer – her first in her new home – as it wiped out her peas and beans and chewed away at her flowering cherry and huge Rosa rugosa.

It took a resource book to identify this creature that is considered the most destructive pest on turf and ornamentals in the eastern United States.

The enemy, she found, had a name: Japanese beetle.

The infestation that first year was immense. Tremblay’s husband, Paul Anderson, was caught in a swarm when he tapped the lawn mower against the base of the flowering cherry that was under attack.

A University of Maine employee, Anderson suggested they seek help from the University of Maine Cooperative Extension. Tremblay contacted the Waldo County Extension educator, Rick Kersbergen, who in turn called Colin Stewart, an assistant professor and homeowner-greenhouse integrated pest management specialist in the Extension’s Pest Management Office in Orono. His is a grant-funded position that began just last year.

It was Stewart who came up with the plan to fight back, one that would involve Tremblay’s neighborhood.

Tremblay called on other homeowners on Rob Clark Road, asking if they, too, had problems with Japanese beetles. She discovered that some did and some did not.

Under Stewart’s supervision, she set up Japanese beetle traps to begin collecting specimens to serve as a comparison for the following years of Stewart’s management program.

“You’re not going to eliminate them,” Stewart said. The best anyone can expect is to control the population.

The method of control is the experiment in Winterport.

Tremblay is doing two things to fight the insects. She handpicks the beetles off plants around her 1-acre lot, and she has six traps set up around the neighborhood that she maintains for Stewart. Once a week or so, in the early morning, she and her 2-year-old son, Isaac, make the rounds, collecting the contents in Ziploc bags, labeling them, making sure they are sealed tightly and then sticking them in her freezer.

The process, she said with a laugh, gives new meaning to the movie title “Beetlejuice.”

After a few collections, the bags are shipped off to Stewart, who is monitoring the number of beetles from each area to establish whether the control methods are working. The experiment will continue for at least another year, if not longer.

With one year of battling the beetles under her belt, Tremblay is spotting changes in this year’s emergence.

“I noticed they are less voracious,” she said during a recent tour of her yard, and pondered whether the cold winter and wet spring had affected this year’s horde.

“They definitely seem to be temperamental,” she said, stressing that it was early in the season – the adult beetles had only been out for 10 days the day of the interview – but she pointed out that her peas and beans, destroyed last year, were being ignored this summer in favor of her potatoes. The flowering cherry in the front yard had some beetle activity, but not a swarm. The rosebushes, however, seemed to be a lure again this year, with hundreds gnawing on the leaves and the late blossoms. Plants that were ignored last year or had been recommended as deterrents, such as four o’clocks, had Japanese beetles chewing on them.

Stewart will test soil samples in Tremblay’s neighborhood in early August, the time when the eggs are hatching. Tremblay is looking forward to the visit, hoping they will discover fewer larvae in her and her neighbors’ lawns.

An organic gardener, Tremblay doesn’t want to use pesticides to control the infestation. Instead, she is hoping to try beneficial nematodes that kill the grubs before they become adults. But it is a tricky prospect: The nematodes are expensive, need to be applied quickly upon arrival and then must be well watered into the turf.

If it works, it may cut down on some of Tremblay’s more unpleasant duties. Just the night before, armed with a dish of soapy water, she spent about five minutes knocking Japanese beetles off the rosebush.

That did in about 300, she said, eyeing the bush still crawling with them.

About Japanese Beetles

The Japanese beetle is a scarab beetle about three-eighths of an inch long, with a metallic green head and thorax and copper-colored wing covers.

There are more than 300 plants that are food sources for the beetle, including trees, shrubs and ornamentals. “They’re not picky eaters,” said Colin Stewart, homeowner-greenhouse integrated pest management specialist at the University of Maine Cooperative Extension Pest Management Office in Orono.

The list of favorite foods includes rose, hollyhock, raspberry, grape, blueberry, bean, cherry, birch, crabapple, linden, black walnut, Norway and Japanese maples, and American and English elms.

They tend to avoid most evergreen ornamentals, including fir, spruce, arborvitae, rhododendron and pine. They usually won’t feed on red or silver maple, euonymus, holly, magnolia and common lilac.

“There are ways to manage pests without using pesticides,” Stewart says. His job at the Extension is to try different approaches to control pests.

The office’s recommendations for the Japanese beetle, are:

. Using traps, only when part of a neighborhoodwide program where they are emptied regularly or in landscapes isolated from other breeding areas. Traps should be placed at least 50 feet from vulnerable plants to draw the beetles away. With a flight range of more than a mile, beetles will travel to traps far from where they emerge, but only some of them will be caught.

. Covering small, highly susceptible plants with floating row cover material.

. Handpicking.

. Irrigating turf selectively.

. Replacing low-value, highly susceptible plants.

. Using beneficial nematodes called Heterorhabditis bacteriophora to control grubs.

. Applying pesticides to highly susceptible, high-value plants to control adults.

. Applying turf insecticides to control grubs.

Other controls include raising the mowing height, which has been shown to decrease pest populations, and planting a complex, diverse landscape that mixes susceptible plants with nonsusceptible plants and provides a succession of blooming plants that attract valuable predators and parasites of pests.

The jury is out on the benefits of milky spore, also called milky disease. The grubs consume the spores, which germinate, develop and kill the grub. But its effectiveness in the Northeast hasn’t been supported with the necessary science, and most experts don’t recommend its use, Stewart said.

As for chemical controls, most pesticides, such as Sevin and malathion, have an adverse effect on beneficial insects, such as honeybees and natural beetle enemies. Rotenone, which is naturally derived, is highly toxic to fish.

A fact sheet about Japanese beetles is available online at http://pmo.umext.maine.edu/factsht/japanese.htm. Or call the Pest Management Office at 581-3880 or (800) 287-0279 to request the fact sheet or to ask for more information about Japanese beetle management.

– Janine Pineo