Managing grubs in the home lawns
Monday morning, June 21, a jar full of beetles was dropped off at the Washtenaw County MSU Extension office. A young lady from Manchester was concerned because these brown beetles were swarming around her trees at dusk, and she was not sure if they were damaging plants in the landscape. This beetle is the European chafer and much like the Japanese beetle, it will be laying its eggs into turf over the next few weeks. Unlike the Japanese beetle, you would not know it is in your landscape because it does not feed on plants as an adult beetle but has emerged from the soil to mate and lay eggs. The grubs from both beetles can damage a lawn if their numbers are high.
To treat or not to treat for grubs
If you are seeing large numbers of Japanese beetles feeding on your plants, there is more than a good chance that they will lay eggs near their favorite plants. Even if you are not seeing Japanese beetles feeding on plants, your turf may still end up infested with grubs from the chafer. I would like to see more people checking for the beetles prior to applying pesticides. Go out at dusk and look up into your trees or even around the roof line of your home. It is easy to spot the European chafers flying around the landscape. If you are seeing only a few here and there do not worry about them, but if hundreds are in your trees every night towards the end of June, it gives you an indication that many eggs are being laid into your turf. The first of July is a good time to apply preventative-type insecticides to manage the grubs as they first hatch out.
For more information on managing grubs, read the MSU Landscape Alert article “First reports of European chafer adults from June 18, 2010.