Invasive Beetle: The European Chafer

Grass. Beetles. Raccoons. Which of these doesn’t belong?

If you've been by Aubrey Davis Park or Luther Burbank Park lately, you may have seen something odd happening to the grass. Perhaps you’ve driven by the home of a neighbor who appears to have rototilled their front lawn.

This “rototilled” look is not intentional; it's actually the work of hungry wildlife seeking to feast on an invasive beetle found in the grass.

An Uninvited Visitor

An invasive beetle – the European chafer – has made its way from the east coast across the country over the last sixty years. In their larval stage, these invasive beetles feed on grass roots, killing the grass and leaving visible dead patches in the turf.

The European chafer is new to Washington. In fact, they were first detected in SeaTac in 2015. The European chafer has been identified here on Mercer Island, and they’ve made it to the top of the dinner menu for local wildlife including raccoons and crows.

It’s a beetle! How can they do so much damage the lawn?

The most severe damage – that rototilled look (pictured above) – is not actually caused by the European chafer or their larvae (pictured below). The damage is caused by wildlife including crows, raccoons, and skunks that are trying to feed on the grubs (larvae) that live in the dirt under the grass. Raccoons will dig and roll away a section of turf for the meal that lives just two inches under the soil. Crows, on the other hand, will pick, pluck, and pull the larvae out of the grass, taking clumps of grass with it.

What can we do to stop this invasive species?

Unfortunately, not much during this time of year. The tell-tale signs of an infestation become obvious when the larvae are at their biggest, beginning in late fall and peaking in early spring.

Early research has shown that healthy, well-maintained and watered lawns are the best deterrent for the invasive beetle. European chafers lay their eggs in grass that is dry, unfertilized, and dirt that is compacted. The best thing you can do for your lawn is improve its health. As you consider options for improving the health of your lawn, keep in mind that the water runoff from your lawn ends up in Lake Washington, carrying pollutants, insecticides, and fertilizer with it.

The European chafer infestation is being monitored and researched here in Washington and across the country. The City is planning a pilot program to reduce the beetle damage in select parks based on this research.

To learn more about how to identify the European chafer, potential solutions for an infestation, or to report a sighting, visit the Washington Invasive Species Council page on European chafers.

How do we stop wildlife from damaging the turf?

According to experts, the most effective way to deter wildlife like raccoons and crows is to make the area around your home less attractive to them. Don’t inadvertently attract their presence with potential food sources. Secure garbage and compost bins. Don’t put out bird seed or pet food. Clean up barbecue areas and don’t put food of any kind into open compost piles. Clean up any fallen fruit from around fruit trees or leftover vegetables from the garden.

For more ideas visit Washington State Department of Fish and Wildlife.

Additional Resources and Information

• Washington Invasive Species Council
• Washington State University Video – European Chafer: A Priority Pest in Washington