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BANGOR – In recent years, few lawn pests have garnered as much attention as the European chafer, an insect that entomologists say first arrived here in the 1940s in New York.
Since then, their grubs, or larvae, have been chomping away at the tender roots of many kinds of grasses, leaving dead patches of lawn in their wake.
The problem isn’t new to the rest of the northeastern United States. Infestations of the chafer’s grub worms have plagued New York and southern New England for decades.
Now they’ve become a problem here in Maine, where for the past two years there have been infestations in the midcoast region and more recently, Greater Bangor.
“It’s ruining the historic district,” Rod McKay, the city’s community and economic development director, told the Bangor Daily News before a meeting about the pests recently at City Hall.
“It brings tears to your eyes,” Gerry Palmer, a city councilor and Hammond Street homeowner, said before the session, which brought together city staffers and insect experts from the University of Maine Cooperative Extension and from the state Board of Pesticide Control.
The topic was the infestation of grub worms that has been killing lawns throughout the Queen City. Among the city employees attending were those who try to keep local parks, playgrounds and cemeteries looking good.
According to the insect experts, the European chafer is to blame for the lion’s share of the problem, accounting for more than 90 percent of the samples they’ve examined in recent weeks. The rest of the grubs they have seen were the larvae of Japanese beetles.
Palmer and his wife, Susan, are among many Bangor homeowners who have been hit by the plague. Like many others, they’ve been searching for solutions to the grub infestation and came to the session armed with a glass jar filled with dirt and dozens of grubs they dug up from their yard.
Sure enough, a quick examination of the plump, wiggly insects confirmed they were European chafers.
During the session, Gary Fish of the state’s pesticide board speculated that chafers gained entry to Greater Bangor through the midcoast region, where a great deal of landscaping and ornamental planting has gone on in the past few years in Rockport, Rockland and nearby communities.
From there, Fish said, the pests spread inland, reaching into eastern Maine and extending as far north as Millinocket, where hotspots have been reported.
Know your enemy
As far as pests go, the grub worms aren’t pretty. Mature grubs have whitish, C-shaped, segmented bodies and brown heads. Think maggots on steroids. To some of those who attended the Bangor bug session, the grubs looked a little like miniature cocktail shrimp.
European chafers complete their life cycles within a year. They lay their eggs in the soil in early summer and those eggs soon hatch into small grubs that spend the next several months devouring grass roots. The larvae then spend the winter deeper in the soil and resume feeding in the spring before emerging as adult beetles in early summer, when they mate and lay eggs again.
In their mature stage, chafer beetles are tan and look much like smallish June beetles. Dill said the adult beetles come out at night and are attracted to light, so the damage tends to be worse under streetlights and security lights and near other lighted places because that’s where the adult beetles tend to lay their eggs.
Because they closely resemble the larvae of other pests common in this area, including those of the Japanese beetle, they can be difficult to identify, noted Clay Kirby, an entomologist at the University of Maine Cooperative Extension’s Insect and Plant Disease Diagnostic Lab.
“People will need at least a magnifying glass and good light,” Kirby said. “We have seen as many as three species of white grubs within 1 square foot of dirt.”
Chafer grubs can be identified by a pattern of short spines located on their tail ends, he said.
While they are in the grub stage they are damaging to lawns, and they do most of that damage in the fall and early spring. They prefer to feast on grass roots, but may move into vegetable gardens and ornamental plantings.
The lawn damage intensifies when the grubs are dug up and eaten by such predators as birds, skunks and, possibly, raccoons, Kirby and his Extension colleague, James Dill, said.
Kirby pointed out that the recently arrived chafer population appears to be “more active, more aggressive” than some of the other types that have preceded it, such as the Japanese beetle.
Ironically, some of the worst damage has popped up on some of the best-manicured lawns, as many have observed.
The experts said that this is because one of the grubs’ preferred grasses, Kentucky bluegrass, is not native to Maine and is cultivated through seeding and sodding. In addition, the chafers don’t care much for dandelions. The weeds have been left intact, even amid otherwise dead grass.
Kirby said observant homeowners and groundskeepers will see large swarms of adult beetles flying off at dusk in late June. He recommends that people who have swimming pools in their yards check their pool filters, which may become clogged with dead bugs.
Now that the culprit has been identified, the focus has shifted on how to attack it.
When to attack
Though healthy turf can withstand some grub damage, bug experts say treatment is warranted when 10 or more grub worms are found within a square-foot-size patch of dirt.
With regard to treatment, the upshot is that there are no easy answers. The grubs can’t be eradicated, only managed, they said.
To that end, there are both chemical and organic options.
Gary Fish, manager of pesticide programs for the state pesticide control board, recommends that homeowners and others trying to manage grub worms should choose the least toxic-method they can.
Either way, the experts said, the smaller the grubs are, the easier they are to control.
The recommended pesticide is imidachloprid, which should be applied once a year, preferably in June or July, when the chafers are in their egg stage, the experts said.
A less-toxic option is to apply nematodes, which are microscopic worms that carry bacteria that excrete toxins harmful to grubs. In the case of grub worms, the nematodes need to be of the Heterorhabditis bacteriophora, or Hb, strain because other strains don’t penetrate deeply enough into the ground.
Nematodes, available at some home and garden stores and through catalogs and Internet sites, work best when soil temperatures reach at least 68 degrees, and while chafers are in the active larva stage.
During the information session at City Hall, City Manager Edward Barrett noted that areas with ground cover plants and shrubs, such as bearberry, bunchberry or vinca, seemed to escape serious grub damage.
Another environmentally friendly, albeit unconventional, approach is to try using the grubs as fish bait, Dill said, adding that “it wouldn’t hurt” to try.
Nature to the rescue
Regardless of what actions are or are not taken, the bug experts say that the problem should begin to abate in the next four or five years, by which time a predator-prey balance should be achieved.
Predators include birds, skunks, moles and raccoons, Kirby noted.
“Plus, a couple of cold winters would help [cut down on the grub worm population],” added Dill.
For more information, the experts suggested visiting the state’s www.yardscaping.org Web site.
dgagnon@bangordailynews.net
990-8189
Got grubs?
For those who aren’t sure if the pests eating their lawns are European chafer grubs, the University of Maine Cooperative Extension’s Insect and Plant Disease Diagnostic Lab provides identification at no cost at its offices at 491 College Ave. in Orono.
Samples should include the submitter’s name and telephone number or e-mail address.
“I’d recommend that they grab a sample of about three to five grub worms,” Kirby said. “I’d bottle them with rubbing alcohol. That pickles them up and makes it a lot easier for us to handle them.”
Added Dill: “What we don’t want is samples that have been sitting in your car in 70-degree [or warmer] temperatures all day,” noting that lab staff already have been faced with some “very aromatic jars of goop.”
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