Those brown patches and holes on your lawn are probably the work of grubs.
Grubs are the larval form of several insects including the Japanese beetle and the European chafer. They’ve overwintered underground and have burrowed back to the surface to feast on the roots of grasses.
If the infestation is bad enough, you can actually roll entire patches of lawn back like a rug to see underneath where the grubs live. If that isn’t bad enough, further grub-related damage can be caused by the small mammals and birds that dig into your lawn looking for grubs to eat.
“I’ve been hearing from a lot of folks about damaged lawns,” said Jim Dill, pest management specialist with University of Maine Cooperative Extension. “Much of what we are seeing now is the crows and skunks having a field day on these lawns and it looks like a bunch of bad golfers came through, or someone with a rototiller.”
The good news is, according to Dill, grub season is just about over in Maine, so the worst of any lawn damage should have peaked by now.
If your lawn has been damaged, there is no point going after any grubs now, Dill said. Instead, the only thing you can do is to replant and prepare for next year.
“The problem becomes if you have grubs this year that means they are in the neighborhood and will lay eggs this year,” Dill said. “By replacing your lawn, all you are doing is laying out a new buffet for next year’s white grubs.”
To control the grubs before they can damage your lawn next year, Dill said your options are limited.
One alternative is introducing a species of beneficial nematodes onto your lawn. According to the Maine Department of Agriculture, Conservation and Forestry, the best one for controlling the Japanese beetles and European chafers are Heterorhabditis bacteriophora nematodes.
Nematodes arrive on a sponge, in gels, granules or liquids, and the best time to apply them is in mid- to late-August on a rainy day or at dusk. Maine DACF maintains a list of businesses that sell nematodes in the state.
The other option is using a chemical pesticide specifically formulated to control the type of grub or grubs eating your lawn. Dill recommends if you are going that route, take the time to get your grubs identified so you know which pesticide to apply.
There is also the option Dill employs, which is to deny the grubs a meal.
“Grubs only eat the roots of grasses,” Dill said. “I have a nice green lawn because all I have growing out there are weeds.”