Beat the Beetles

Japanese Beetles

Pauline grew and pampered her grandmother’s heirloom roses with pride each year. In March they had just began to leaf out, by May they were magnificent, but come July and they were desiccated skeletons. Like many gardeners in the Washington, DC-area, Pauline’s had been attacked by Japanese Beetles. They can do devastating damage often stripping a whole plant from top to bottom. How can we fight back?

Know the enemy

Japanese Beetles first arrived in New Jersey about 90 years ago by accident. Since then they have multiplied exponentially. Each female beetle can lay about 50 eggs each during their active summer season. Without their natural predators and diseases from their native Japan, they have thrived and spread throughout the eastern United States.

One of the most hated pests around, they have few virtues other than providing nutrition to birds. The good news is they are only active in your garden from the end of June to late August. The bad news is they spend the rest of the year in their larval stage as white grubs eating your lawn grass roots.

You will notice that the beetles are attracted to certain plants over others. They will strip a hollyhock or grape vine bare, while letting your boxwoods, azaleas, and holly alone. This is due to certain plant scents that are highly attractive to the beetles. You can plant your garden full of beetle resistant varieties or you can read on for practical ways of fighting this local garden scourge.

Japanese Beetle

Engage in hand-to-hand combat

The most effective way of dealing with a small infestation of Japanese Beetles is picking them by hand. I know it is not the most pleasant way to spend a summer morning. However, the more you can get rid of now, the fewer that will be around to lay more eggs and come back next year.

Beetles eat in groups and while feeding they give off odors that attract others to the damaged plant. In addition, each female beetle excretes a chemical that attracts male beetles to her in droves. By manually cutting down on their number, you will automatically get rid of the chemical scents that attract more to your garden.

Put on gloves and fill a bucket with soapy water. Go out before 8:00 am while the beetles are still sluggish and shake the infested plant over the bucket. Pick off any beetles that stay on the plant.

Pull out the bug guns

Dave McDonald of St. Gabriel Labs in Orange, VA, says, “This year is an especially heavy one in terms of Japanese Beetle population. We are getting reports of increases throughout Virginia, Maryland, and up into Pennsylvania.”

“It just seems to be a perfect climate year for them – the level of moisture, warmth, and general weather conditions – all came together to make a perfect mix for the beetles to thrive,” McDonald explained. Well, that is great news for the bugs, but tragic for home gardeners.

Some gardeners are facing a situation where the beetle numbers are so large, they are forced to go to drastic measures and resort to chemicals that kill all bugs in their yard. This can be especially destructive to our area’s vulnerable honeybee population.

St. Gabriel Labs distributes Milky Spore, which is one of the first lines of attack for home owners doing battle with an entrenched Japanese Beetle infestation. Milky Spore is a naturally occurring host specific bacterium. It is lethal to the white grubs of Japanese Beetles and does not harm other creatures or plants in your garden. With the spore you are targeting the beetles at their most vulnerable stage.

Milky Spore is available at your local garden center and comes in two forms – powder for a one-time application or granular which is applied three times for two years in a row. Once applied the spore is guaranteed to kill the grubs and prevent Japanese Beetles for 10 years in your yard.

That is great for getting rid of your infestation, but what if your surrounding neighbors are also infested and you’ve got beetles coming over from next door? McDonald says St. Gabriel offers a service that is popular with local home associations. They come out and apply Milky Spore to an entire townhouse community to insure a Japanese Beetle-free environment for all. It is usually paid for out of the association dues and has proved to be very popular recently.

For more information on environmentally safe beetle combat, visit www.hgic.umd.edu/documents/hg78.pdf, www.milkyspore.com, or www.uky.edu/Agriculture/Entomology and do a site search for “Japanese Beetle.”

Photos by Drena J. Galarza, Washington Gardener Magazine.

About the Author

Kathy Jentz
Kathy Jentz is editor of Washington Gardener magazine and is a long-time DC area gardening enthusiast. Washington Gardener is all about gardening where you live. She can be reached at @WDCgardener on Twitter and welcomes your local DMV gardening questions.