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Don’t Just Bag Those Beetles – Control Them in Turf

Posted: August 24, 2015

It is usually mid-summer when we start to see many of our trees, shrubs and vegetable plants in our landscapes with skeletonized, chewed leaves and in some cases they are almost completely defoliated by August.

Japanese beetle are the main culprit and they can often be found on roses, cherry, apple, birch, elm, and linden trees, as well as zinnias, ivy, and marigolds. The adults feed on nearly 300 different host plants.

They were first found in the United States in 1916 near Riverton, New Jersey and strategies to manage the larval and adult stages are estimated to cost over $460 million each year.

Life Cycle

In order to properly control Japanese beetles in your garden or landscape, you must first understand its life cycle. The species of beetle overwinters as larvae (white grubs) in the soil. As the weather warms up in the spring, they move towards the soil surface and feed on grass roots. Larvae mature in late mary through June and molt to pupae in the soil. A good indicator of a grub problem is night time digging and feeding by skunks your lawn.

Once the Japanese beetle adults emerge from the soil in late June, they begin to feed on ornamental plants, chewing foliage between the leaf veins or skeletonizing.

Control

The best way to control Japanese beetles is not to attract them to your yard with a “Bag-a-Bug” device which contains a synthetic sex attractant or lure.  Those devices were originally designed as a monitoring device and will probably attract more Japanese beetle to your yard than you already have. Control strategies should be targeted at the next generation that will begin to hatch and feed in the lawn in late summer.  Several biological controls exist including parasitic nematodes, or Milky Spore, a fungus that will attack the grubs in the soil.  Insecticidal control measures can be applied to your lawns in late-summer/early fall. It is best to apply materials late in the day because grubs move up in the soil to feed during the evening.

If you have grub problems, avoid the desire to “attract and bag” them and prepare to control them in the turf later this summer when they are young, hungry and vulnerable.

For more information, view our factsheet on Japanese Beetle Control or call your local Extension Office.

Contact Information

Vincent Cotrone
  • Extension Urban Forester, Northeast Region
Email:
Phone: 570-825-1701