Have you noticed leaves stripped bare of greenery in your garden or around the lawn?
There’s a good chance the culprit is a Japanese beetle … or a whole host of them.
The invasive insect is at or nearing its peak population for 2025, according to Dr. Elizabeth Lamb of the Cornell Integrated Pest Management Program.
The distinctive green and bronze beetles are conspicuous in their appearance and in the effect they have on many plants.
“We notice them because they’re gorgeous. If they weren’t an annoyance, they’d be beautiful,” Lamb said. “Usually, you see the Japanese beetle and the damage. They are out heavily during the day. It’s not hard to see them.”
A Japanese beetle on a closed hibiscus flower in Chesterfield, Virginia on June 28, 2025.
Here’s why they are considered such a pest, and how to protect your plants from beetle damage.
Japanese beetle life cycle
Japanese beetles begin their life cycle as an egg in the soil. Beetles especially like laying their eggs in irrigated turf, Lamb said. They develop into a grub that feeds on roots, potentially damaging grass and crops.
After going through various larval stages, they pupate and emerge from the soil in the summer months as adult beetles.
A Japanese beetle feeds on the leaf of an oak tree.
Once topside, Japanese beetles have three primary urges.
“They mate, eat, lay eggs, and die,” said Lamb. “Once they lay their eggs, the cycle starts all over again.”
Japanese beetle damage
Japanese beetles have a large appetite for hundreds of plant species. Unfortunately, many of their favorites happen to be common in home landscapes. Roses, crabapples, hydrangeas and azaleas can be particularly hard-hit, as well as crops like corn, grapevines and beans.
Leaves visited by Japanese beetles can be left with a skeletonized appearance, sometimes with only the veins remaining untouched.
“There’s two things we don’t like, the feeding of the adults and the feeding of the larva. What we’re seeing now (in the summer) is the feeding of the adults,” said Lamb. “They like roses and a lot of the stuff we like to look pretty.”
Japanese beetle damage on a canna lily leaf in Chesterfield, Virginia has a lace-like appearance.
Japanese beetles often feed at the top of trees, where damage may go unnoticed. Lamb said Japanese beetles can even damage the crops of Christmas tree growers as they feed on the leaders.
“In a home garden situation or a home landscape, you might not notice them on the leader because the leader is up over our head,” Lamb said. “Where people really get annoyed by them is if they’re on something that’s an ornamental and they want it to look beautiful, or if it’s on a food crop damaging the part we want to eat.”
How to control Japanese beetle populations
Damaged leaves attract more Japanese beetles into the area, leading to large infestations on some plants. While Japanese beetles typically do not kill trees or shrubs, their feeding can stunt growth, and regular defoliation can weaken plants and make them more susceptible to diseases and other pests.
Their proclivity to gather in large numbers does make Japanese beetle removal an easier task.
“It’s much easier to control them if they’re all in one place because you can knock them into a bucket of soapy water,” Lamb said. “You can usually get a lot of them at one time. It makes you feel like you’ve accomplished something.”
A Japanese beetle sits on a swamp rose bush.
A variety of Japanese beetle traps are also on the market. They utilize a pheromone that draws beetles in and catches them in a plastic bag. Lamb recommends placing the traps far from plants you want to protect as the pheromone is quite effective in attracting the beetles.
“You can pull in a lot with the pheromone and you will catch a lot,” Lamb said. “The question is always, do you catch enough to reduce the population in the plants that you’re trying to save? It’s one of those decisions that is up to you.”
The best way to reduce Japanese beetle numbers may be neutralizing them long before they ever land on your prized plants. Nematodes that attack Japanese beetles can be applied in late summer when the larvae are small and highest in the soil. Species like heterorhabditis bacteriophora are commercially available, Lamb said.
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“The problem is if you kill every one in your yard right now, more will fly in. It’s just not a good system,” Lamb said. “If you can control grubs in the soil, that’s a better place to do it.”
Like most invasive species, Japanese beetles have few natural population controls in the ecosystem. Lamb noted that peak populations can vary year to year, influenced by factors like a harsh winter or a wet spring, but chances are they will turn up sooner or later.
“If you have a tolerance of zero Japanese beetles, that’s hard to maintain in peak adult season,” Lamb said. “They certainly do vary in number from year to year, but as homeowners it’s like ‘Oh, Japanese beetles. Ugh.’ When we don’t see them we’re happy, and when we do see them we’re not.”
This article originally appeared on Elmira Star-Gazette: Japanese beetle population is peaking. How to protect your plants