First reports of European chafer adults
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Two people called me this week to report large numbers of these light brown beetles swarming in their trees at dusk. European chafers emerge from the ground in the early evening and gather up in huge mating flights. The flights occur at sunset and often times the swarms concentrate around a tree or shrub.
A few years ago Capital City Airport reported the beetles were swarming around and on the tails of jet aircraft. Both recent callers said they thought the beetles were honeybees because of the large numbers involved and the loud buzzing sound they made. The swarming behavior doesn’t last too long, 30 minutes to an hour tops, then the beetles settle down on the foliage where mating takes place. The adult beetles are reported to just nibble on foliage or not feed at all. However, one caller this week said the beetles were eating the needles of her pine tree and stripping the bark off the trunk.
Females burrow into the soil a few inches the day after mating and lay their eggs singly in earthen cells. The eggs hatch in two to three weeks. The tiny white grubs immediately begin to feed on grass roots and continue to do so, undergoing two molts, until the freezing ground drives them deeper into soil away from the root zone. In the spring, as the soil warms, the grubs follow the retreating frost back to the surface where they commence feeding on the grass roots. Larval development is completed in late May and the grubs pupate to transform into adult beetles and the life cycle begins again.
The European chafer is the most destructive turf pest in Michigan. It occurs throughout the state including the Upper Peninsula. Those with a history of turf damage by these white grubs should consider treating their lawns with products containing imidacloprid or halfenozide around the first of July.