The voracious, barbarous hordes plagued their favorite pillaging grounds — plants and trees situated east and just west of the Mississippi River last year. This includes our bounteous Mahoning Valley.

You guessed it — they are the despised, dreaded, destructive and ugly Japanese beetle (Popillia japonica).

They are the scourge of turf grass growers at golf courses, grape growers, and home vegetable and flower gardeners. These nasty critters are the embodiment of what happens when an invasive species with no natural predators finds an environment with a smorgasbord of more than 400 species of trees, shrubs and nonwoody plants on which to dine.

Since this beetle species hitchhiked to New Jersey in 1916, they have thrived by eating and defoliating their way across 22 states. This summer, they were spotted for the first time in the northwest — both in Oregon and Washington. Wherever they go, they become a threat to our plants and our sanity.

The worst of the adult Japanese beetle feeding frenzy occurs when we start seeing the adults (sometime after the Fourth of July, depending on growing degree days). They last through their heaviest numbers in early August. There are some strategies to prevention, control and management of these serious plant pests. At each of its life stages, the Japanese beetle causes significant damage.

The female adult beetle feeds on suitable plants, then mates and places eggs in the soil, where they absorb moisture and develop into typical white grubs. Our OSU Extension factsheet describes how overwatering can contribute to the development of grubs and the destruction of turf grass roots and unsightly brown spots on the lawn or golf course fairways.

The grubs develop into pupae, then adult beetles, which emerge on warm, sunny days and as a group skeletonize our shrubs, trees, plants and flowers.

I offer one natural control strategy that can help reduce the damage of Japanese beetles: hand pick and place them in a container with soapy water. The practice isn’t as gross as it sounds. Making it into a game provides some entertainment, along with the feeling of satisfaction you feel when they are meeting their demise.

Simply fill a pail with a solution of 1 tablespoon dishwashing detergent in water and simply knock the beetles in, where they will sink and quickly drown. One morning I rapidly and efficiently got rid of more than 100 beetles chewing on my favorite hydrangea. They seem to congregate on one or two plants, which makes this process easier.

There are a number of other safe ways to get rid of Japanese beetles. If you choose to use insecticides, please carefully read and follow the directions on the container to protect other insects, pets, wildlife, and humans.

Beetle traps have proven to attract more beetles than you would have without them. More beetles means even more damage to your plants. Thus, they are not recommended.

For more on managing and controlling Japanese beetles, go to http://go.osu.edu/japanesebeetles .

Novotny is an Ohio State University Extension Master Gardener Volunteer in Mahoning County.