The usual wave of Japanese beetles has been sweeping through the Erie area this summer, leaving chewed leaves, weakened trees, and frustrated homeowners in their path.

“These beetles have been in the U.S. for over a hundred years,” said PJ Liesch, an entomologist at the University of Wisconsin–Madison. “The first detections were in the Philadelphia area, and they’ve spread outward from there. Now, places like Pennsylvania and the Great Lakes states see very heavy activity.”

Japanese beetles are a non-native scarab beetle species originally from East Asia. While their shiny green and copper shells might be eye catching, their appetite is destructive. “Some of the top things they go after are birch trees, linden trees, rose bushes, grapevines, and fruit trees like apples,” Liesch said. “But when populations get high, they’ll spill over to just about anything green.”

On top of that, PJ pointed out another interesting Japanese beetle fact: beetle damage attracts even more beetles.

“When they nibble on a plant, the plant releases chemicals into the air,” Liesch said. “It’s like blood in the water for sharks, it attracts even more beetles. That’s why early intervention can make a big difference.”

Homeowners hoping to protect their yards should tailor responses based on their individual situation. Liesch recommends hand picking beetles and dropping them into soapy water, especially early in the season. “Scientific studies have shown it really can make a difference,” he said.

Other effective strategies include mesh netting to block beetles from smaller plants or simply tolerating moderate damage, especially on healthy trees. “Trees can often handle 20 to 50 percent defoliation and still do just fine,” Liesch said. “But repeated full defoliation year after year can stress them out.”

For more severe outbreaks, organic and conventional sprays are available at local garden centers. “Educate yourself, assess your space, and do what makes sense for your yard,” Liesch said. 

Next time you and your yard enter a Beetle Battle, you'll be-etle more prepared!