Gardeners battle Japanese beetle infestation

Posted at 7:30 PM, Jul 18, 2017
and last updated 2017-07-18 22:18:36-04

If you garden or have a house with a yard, chances are you've encountered this pesky nuisance: Japanese beetles.

They're back this year, and in bigger numbers than before.

The beetles feed on about 300 different of plants and are an invasive species. Experts say by the time you've spotted them on your plants, it's probably too late. 

"It'll probably get worse in the next couple years. We're experiencing sort of the height of the invasion wave at this point," said Jonathan Larson, University of Nebraska-Lincoln Extension etymologist.

It's that time of year when Japanese beetles emerge from the soil to swarm vegetation. They can possibly kill smaller plants or newly transplanted trees by skeletonizing leaf tissue.

"When they bite something they like, theres some chemicals and sugars in that plant that they find palatable and tasty, so they bite it. They eat more of it, and the plant produces a smell that attracts other beetles to that plant," Larson said.

The best course of action is to treat the base of trees and shrubs with insecticides in May — around Mother's Day — before you see the insects flying around. Once the bugs appear, plants not in bloom can be treated with some insecticides.

"Japanese beetle response to disturbance is to drop straight down. So if you hold a bucket of soapy water beneath that, and tap that branch, they drop right down into that soapy water, and it's a very effective means of keeping their numbers down," said Kathleen Cue, horticulture program coordinator. 

Pheromone bag traps are generally warned against; they do the job a little too well. 

"It can attract thousands, hundreds of thousands of beetles to your property. The bag itself can only hold about 300, and you get a few bags to replace the original one, so you're taking it down and replacing it every day. You're only catching a thousand beetles, maybe, compared to the 100,000 that were attracted to your property," Larson said.