Friday, September 3, 2021

Japanese beetle count passes 20,000

Amber Betts
WSDA Communications

There have been more than 20,000 Japanese beetles caught in Grandview this summer. Sound the alarm, ring the bell, this is not good news. If established in our state, we could see dire results to our crops, our gardens, and even our grass.

These invasive beetles almost double the human population in Grandview, and it keeps climbing. Our Pest Program staff are working to determine just how widespread the beetle has become.

So far, the beetles are being detected in the highest numbers in the residential area of Grandview. A few, however, have crossed the road into rural areas where the crops many people rely on for our living are found. Adult Japanese beetles love to feast on more than 300 plants, including roses, grapes, apples, hops, and grass. They are highly destructive, difficult and expensive to eradicate or control.

Japanese beetle (Popillia japonica).
What is a Japanese beetle?

The Japanese beetle (Popillia japonica) is a garden pest native to northern Japan. The adults eat the leaves, buds, and flowers of plants while the larvae attack the roots, particularly the roots of grasses.

How did they get here?

We’ve been trapping for Japanese beetle since the 1980s and occasionally find that they’ve caught a ride to our state, normally on a plane from an infested area in the Eastern U.S. But it has been more than a decade since even a single beetle has been detected beyond the vicinity of an airport. The larvae are found in soil associated with the roots of host plants, they are common under turf or sod and can be moved in potted plants.

What are we doing?

If you’ve been in Grandview at all in the recent months, you have likely seen traps hanging all over the city. That’s us, trying to determine the extent of the infestation. At the end of the season, we will look at the data we’ve collected and begin formulating a plan on how to eradicate these pests.

What can Grandview citizens do?

If you live in Grandview and have hung Japanese beetle traps, please report your trapping results. If you have seen the beetles on your property, consider treating your lawn following WSU’s treatment guidelines. Not all products labeled to treat your property for Japanese beetles are effective; WSU’s guidelines let you know which ones can work and how to properly apply

What happens next?  

Trapping for Japanese beetles will continue at least through September, after which our staff will begin removing the hundreds of traps currently in the area. The trapping results will inform both the eradication plans which are anticipated for next spring as well as a quarantine which is being considered to prevent the unintentional movement of the beetles into beetle-free areas of the state.

Get email updates on our progress and join our Japanese Beetle Watch Facebook group for the latest information and to connect with others working on responding to this introduction.