A new and potentially very destructive lawn pest has been discovered for the first time in Minnesota this year. The European chafer beetle was found in a lawn in south Minneapolis this summer.
According to the Minnesota Department of Agriculture, the European chafer beetle (Amphimallon majale) can be more destructive to lawns than Japanese beetles because it has a longer feeding season as a grub. The beetles have been in North America since 1940, mostly confined to the East Coast and southern Ontario. They have now spread to Michigan and in 2013 beetles were discovered in Wisconsin.
The adult beetles are a reddish, golden brown and are only active for a week or two each year. When summer night temperatures are warm (above 65 F.), they emerge just before sunset from the turf where they spend their days. They may appear in swarms and they mate like crazy usually on trees and shrubs that are close to the ground. After the mating period is over, you may see chafer carcasses on the ground. The adult beetles do not damage anything, they just make more beetles.
Each female chafer beetle will lay 20 to 40 eggs underground. The eggs hatch a few weeks later and spend the rest of the summer as grubs, feeding on roots in the soil. In November, the grubs move lower in the soil to get through winter. They become active again in spring, and in late spring, pupate before hatching as beetles in June or July.
Damage to Lawns
Most of the damage to lawns is seen in late summer or early fall after the grubs have emerged. One additional problem with the chafer beetle grubs is that they are a particularly tasty snack for crows, raccoons and other animals, who dig up the lawn looking for the grubs to eat. Treatment options include keeping your lawn very well watered during the mating and egg laying season (the beetles don’t like to lay eggs in wet soil) or using a chemical option on the grubs.
At this point, the European chafer beetle is not a common lawn problem in Minnesota—lawn damage is more likely to be caused by Japanese beetle grubs or other issues. The University of Minnesota has a great information on lawn problems. If you think the European chafer beetle is in your lawn, contact the Arrest the Pest line at the Minnesota Department of Agriculture.