Know your nuisance: Japanese beetles

Published 7:05 pm Thursday, July 7, 2011

Adult Japanese beetles usually emerge from the ground in mid-June and munch on flowers and foliage, leaving large holes in leaves, until the end of July. Above, these beetles have chewed up the hibiscus and chinaberry trees in the personal garden of Tim Johnson, who owns Johnson’s Gardens on Holland Road.

Editor’s Note: This is the first in a series of stories about garden nuisances. Watch the Home & Garden section on Fridays for the reminder of the series.

The Japanese beetle hasn’t always called Virginia home, but it has made a comfortable residence here with a plentiful supply of food in the area’s trees and plants.

The beetle’s constant munching of flowers and foliage has earned it a nasty but deserved reputation as a garden pest.


Email newsletter signup

Originally from Japan, the beetle was first found in the United States in 1916, according to the U.S. Department of Agriculture.

In its native country, there were natural predators to keep the beetle population in check, but the United States offers it a home free of predators and full of food.

Adult beetles start coming out of the ground around mid-June, and they tend to stick around until the end of July.

Greenhouse manager Jeff Williamson of Smithfield Gardens on Bridge Road said gardeners come into the nurseries complaining about the bugs during this time of year.

Adults feed on hundreds of varieties of trees, shrubs, vines and vegetable plants and leave behind large holes in leaves.

The grubs grow in the ground and feed on the roots of plants and can do damage of their own.

Williamson said he gets most of his complaints from areas in Isle of Wight County and southern Suffolk from people who say the beetles are eating their trees bare.

“They go after a lot of plants,” he said. “They can do a lot of damage especially in high numbers.”

Williamson said a few of the beetles’ favorite plants that grow in this area include crape myrtles, purple leaf plums and roses.

“Roses are the one thing they really gravitate to,” he said.

Tim Johnson, the owner of Johnson’s Gardens on Holland Road, said the beetles seem to really enjoy hibiscus and chinaberry trees as well.

In order to rid your garden of the beetles, Williamson suggests one of two methods: using chemicals or using beetle traps.

Williamson recommends gardeners use the chemical carbaryl, which can be mixed with water and sprayed on the infested plants.

He said it is important to ensure the spray hits the beetles because it is otherwise ineffective.

Also, he said the spray should be reapplied if there is a lot of rain because the chemical washes off with water.

Another solution to getting the beetles out is to use Japanese beetle traps, which are available at most garden stores.

The traps use a floral lure to attract the beetles and have a slippery surface that causes the bugs to fall into a bag.

Williamson said in order for the traps to work, they have to be placed at least 50 feet away from the garden.

“You want to get it away from those desirable plants,” he said.

If they are placed in the middle of the garden, they will only attract more beetles to eat the plants, he said.

Johnson has a different approach to the beetle problems.

He tells his customers to ride out the short beetle season and ignore them if there aren’t excessive amounts of the bugs.

Johnson said the best thing to do is to pick the grubs out of the ground after July to keep the beetles from returning the next year.