Japanese beetle control information provides gardeners with tips to help them get rid of the pesky Japanese beetles (Popillia japonica). Whether you’re dealing with Japanese beetles on basil, on morning glories, or on ornamental trees and shrubs, they are a problem.
Identifying Japanese Beetles
Adult Japanese beetles are easy to spot. They’re flying beetles with pretty, coppery-colored wings and an iridescent green head. Adult beetles are about 3/8 of an inch long. Here in Virginia, Japanese beetles emerge in June, usually around the second week. The adults live only a short time to feed, mate, and lay eggs. In the meantime, they can wreck havoc on your plants.
Signs of Japanese Beetle Damage
Japanese beetles eat leaves, fruit and vegetables. Leaves look like lace after Japanese beetles get through with them. If you have a really severe infestation, plants can be damaged or outright killed. Mature trees and shrubs usually survive. Some garden vegetables like green beans can look really bad but continue to produce beans. Others may need more TLC after the Japanese beetles get done with them.
Japanese Beetle Life Cycle
Now is the time when the beetles emerge as adults, seek mates and food, lay eggs and yes…die.
Japanese beetles lay their eggs in the ground. The larvae hatch from the eggs and eat the roots of your grass or plants. Brown patches in lawns during the winter and spring may be signs of Japanese beetle infestations. They kill grass as they chomp through the roots.
Once the larvae pupate, they turn into adult beetles and emerge from the ground in early to mid June. Females secrete a special scent that humans can’t smell called a pheromone. This chemical is “hey baby, I’m available!” scent to the males, who use it to find eligible females for mating. By late July, the females have mated and tunneled back into the ground to lay eggs and die, thus completing the life cycle.
How to Get Rid of Japanese Beetles
Now that you have an inkling about the life of the Japanese beetles, you may understand a little of what I meant by Japanese life cycle control. The truth is, Japanese beetles are imported insects that made their way into the United States around 1917. They left behind their nature predators in Asia. Thus we have beetles who are prolific, bad for our crops, and without natural predators. Not a good situation.
To get rid of Japanese beetles, you have to disrupt them at every stage of their life cycle.
Organic Japanese Beetle Control
There are a few methods of organic Japanese beetle control. First, clean up any weedy areas near your garden. Japanese beetles eat almost anything but are especially attracted to Virginia creeper, wild raspberry and blackberry bushes, sassafrass and wild grape are attractive to Japanese beetles.
Next, plant varieties of fruit crops that are unattractive to beetles. Certain varieties of blueberries, raspberries, and apples, for example, are more resistant to the beetles than others.
You know those droughts in July and August that plague Virginia gardens? Count your blessings. Droughts and dry weather kill off some of the eggs in the soil, making next year’s population smaller.
Nematodes, specifically Heterorhabditis, are an effective biological control. These can be applied to the lawn in August, watered in, and left to destroy many of the eggs.
Japanese Beetle Control Through Traps
Traps are controversial. Some people swear by them, others swear at them. The Virginia Cooperative Extension website doesn’t warn against using them. I visited the Kentucky Extension testing site and their research also shows that they do not attract more beetles to the garden (a common myth about Japanese beetle traps).
Traps use pheromones, those come-hither chemical signals secreted by female Japanese beetles, to attract all the boys into the trap. The thinking goes that if the males are trapped, the females have a tougher time finding mates. Some traps may act on both males and females.
No matter what, you’re going to have a bag of dead beetles to remove in the hot weather if you use traps. And they smell bad. Really bad. Trust me on that one. If you opt for traps, the risk is that it will attract MORE Japanese beetles into the area. Think about it this way: the pheromones are advertising free sex. Don’t you think that’s going to attract more males? I’m thinking, “Hmm….yes.” Right.
So that’s the risk, but the reward is less damage to your garden plants. You may want to test traps out. Hang them 30 feet away from the garden plants that are under attack to lure adults away from the foliage.
Chemical Controls and Sprays
There are several approved chemicals you can use on lawns and sprays for plants. Michigan State University offers a complete list along with appllication instructions.
Chemicals effective against Japanese beetles include:
- carbamates Sevin and Lannate
- organophosphates Guthion and Imidan
- pyrethroids Danitol, Asana, Brigade, Baythroid, Mustang Max, Warrior and Capture
Japanese beetles are tough to get rid of, but with a little planning and yearlong vigilance, you can at least reduce their numbers. Good luck and don’t fret too much. By August, they’ll be gone.
But I’m sure something else will take their place.
Garden Journal: Japanese Beetles in Southside Virginia
At this time of year, one of the most frequently asked questions is how to get rid of Japanese beetles. The Japanese beetles here in Virginia arrived last weekend with a flourish. I was walking Shadow out onto the lawn for a quick potty break and she brushed against the dogwood tree planted near the corner of my home. The tree erupted into an angry buzzing swarm of beetles, and as I flapped my hands around my face like I was taking off from a heliport, I realized that the Japanese beetles were back.
They’re like that. You can be gardening merrily along, and suddenly in one weekend you’ve got an invading swarm of pesky beetles munching on all your plants.
This post was written July 2016. It was updated on June 22, 2021 with new images, updated information from the cooperative extension office, and improved formatting.
Jeanne Grunert is a certified Virginia Master Gardener and the author of several gardening books. Her garden articles, photographs, and interviews have been featured in The Herb Companion, Virginia Gardener, and Cultivate, the magazine of the National Farm Bureau. She is the founder of The Christian Herbalists group and a popular local lecturer on culinary herbs and herbs for health, raised bed gardening, and horticulture therapy.