Have the “jitterbugs” invaded your yard this year? If so, the foliage of any number of your plants, shrubs and trees has been left skeletonized. You may also be noticing patches of dead grass in your lawn that can be easily lifted off the soil.
In their iridescent green and gold coats, adult jitterbugs swarm on fruit trees, ornamental trees, shrubs, vines, and flowers and feed on the foliage and fruits of these yard and garden plants. And these bugs are not only harmful as adults. Even as
grubs living beneath the soil, they feed on the roots of grasses and plants.
Some years ago, when I first heard the term “jitterbug,” I pictured a small ladybug type insect that rested harmlessly on the leaves of different plants and just, well, “jittered.”
The real jitterbug may have acquired this nickname from its habit of lifting its spiny, back legs into the air when disturbed. However, it came by the name, the Japanese beetle is no stranger to the yards and gardens of our area.
In its native Japan, Japanese beetles are controlled by natural enemies that keep them from being serious pests. But in the U.S., the beetles are able to cause serious, widespread damage. Japanese beetles first entered the U.S. in 1916 through a nursery in New Jersey and, without natural enemies here, they quickly spread throughout the country.
Japanese beetles live for one year and, as adults, they usually begin to appear on plant foliage during late June and July. Early arrivals look for favorite food plants and begin to chew tiny holes in the leaves. These first beetles emit an odor (pheromone) that attracts other beetles to the feeding area. As the insects gather, mating takes place, and the females begin to lay eggs in the upper two to four inches of the soil around the plants where they are feeding. Egg-laying continues until mid-August, while adult beetles may continue feeding until frost. As the eggs hatch in eight to 14 days, the grubs feed on plant roots and organic matter in the soil. By late October, the grubs dig deeper to over-winter. Grubs climb to the surface again in the spring and feed until they have developed into adult beetles. As adults, they once again emerge to feed on your yard and garden plants.
Other than their period of hibernation during the cold months of the winter, Japanese beetles are very destructive to plant life throughout their life cycle. In their larval stage, these beetles are considered the most widespread turf-grass pests in the U.S. For homeowners, skeletonized foliage on plants and dead patches of turf are probably being caused by jitterbugs in adult and larval forms.
There are a number of approaches to dealing with Japanese beetles. Some of these are:
• Hand picking. This control is most effective if it can be done when the beetles first arrive on a property. By removing and destroying the early arrivals, homeowners can prevent them from attracting other beetles. Adults are usually more easily caught in the early morning or late evening and can be destroyed by dropping them into a container of soapy water. It is also easier to spread a sheet under a plant and shake it to dislodge the beetles. Then gather them from the sheet.
• Chemical controls. There are a number of chemical pesticides that are effective against Japanese beetles. Some of these are: Orthene, Sevin, Bayer Advanced Tree and Shrub Concentrate, etc. When using chemical controls, always follow closely the instructions on the container.
• Planting non-host or companion plants. There are many common yard and garden plants that do not attract Japanese beetles. Varieties such as: arborvitae, begonia, bleeding heart, caladium, carnations, columbine, celosia, coral bells, coreopsis, daisies, dogwood, euonymus, firs, forsythia, hollies, hydrangeas, junipers, lilies, nasturtiums, red and silver maple, pines, poppies, violets, pansies, yews, burning bush, boxwood and spruce are resistant to the beetles.
Also, catnip, chives, garlic, and tansy planted near susceptible plants may help repel the beetles.
• Grub control. Insect parasitic nematodes are now available to use for destroying grubs. Look for Biosafe, Biovector, Exhibit and Scanmask. Follow the directions for use on the containers. Grubs are best controlled when they are small and actively feeding.
• Beetle traps. Pheromone traps have been widely used but research carried out by many U.S. extension service branches have shown that these traps attract many more beetles to you yard than they catch.
Though the jitterbugs have invaded, consistent, defensive action can help to keep them under control. Without the natural enemies in Japan that help to limit their harmful behavior, we will have to take that role until natural means can be found to reduce their destructive effects on the trees, shrubs, and plants in our backyards.