BANGOR, Maine — Now that some warm, sunny weather finally has arrived, Mainers are expected to head outside for some much needed yardwork.
And after the rash of grub worms that wrecked lawns and fields throughout the region last year, many Mainers might be tempted to start applying pesticides or beneficial nematodes now.
Insect experts in Maine said that the grubs, or larvae of the European chafer, were to blame for the lion’s share of the damage done to yards and parks last year, accounting for more than 90 percent of the samples brought to them for identification.
During the early stage of their life cycle, before they become adults and fly away in late summer, the grubs chomp away at the tender roots of many types of grasses, leaving dead patches of lawn in their wake.
Though lawns are starting to green up, it is not the right time to start treating yards and parks to prevent a repeat, James Dill, a University of Maine Cooperative Extension pest management expert, said Friday.
Simply put, he said, taking action against grub worms too early is ineffective and a waste of homeowners’ time and money.
According to Dill, the best time for weekend warriors to attack their grub problems is after mid-June if they plan to go the chemical route and use pesticides.
The optimum time for applying beneficial nematodes, or microscopic worms that carry bacteria that excrete toxins harmful to grubs, is late July and early August, Dill said.
That’s because both options are designed to attack the grubs in their early stages, namely while they are still in the egg or early larval stages.
According to Dill, the only effective measure at this time is to hire a professional landscaper who is certified to use chemicals not available to the general public.
According to Dill and other pest experts, healthy turf can withstand some grub damage. Treatment is warranted only when 10 or more grubs are found within a square foot of dirt.
On a positive note, Dill said grub damage this year might not be as bad as it was last summer, in part because many people treated their turf and laid down new sod or reseeded.
He also said that some of the chafers that burrowed underground have been killed off by freezing temperatures, though the region did not see as hard a ground freeze as it sometimes does because of the thick layer of insulating snow.
Though it’s still early in the lawn and garden season here, Dill said his office already has examined grub samples brought in by a local landscaper.
“All those grubs that were in the ground are now adult [chafers]. They’ve done about 90 percent of their eating and they’re probably fat and happy down there,” he said.