Best Ways to Get Rid of Japanese Beetles

Since finding its way from Japan to the southern parts of the state of New Jersey, the Japanese beetle has devoured a path across the United States. The beetle has plowed through the fruits, foliage, and roots of more than 200 different plants including ornamentals, lawn grasses, vegetables and more without a single natural enemy that it has in its native Japan. With efforts to control them exceeding more than $460 million dollars every year, read on to find out about some of the best ways to get rid of Japanese beetles.

Check for Infestation

An evaluation of whether or not you have a Japanese beetle problem must first be done before any type of control program is initiated. Small numbers of the insects do not pose a problem, and it is not recommended to treat your lawn or garden area if this is your situation. However, large populations of the beetles, either in adult or larval stages, should be a warning to take action.

Traps made for the purpose of catching the beetles are not meant to work toward killing the pest, but to determine how many adults have invaded your property. A few Japanese beetles caught in traps do not mean you have an infestation; if a trap is filled, you do need to take steps to cut down on them (complete eradication is not possible).

To determine grub (larval) infestation, dig a foot square by three-inch-deep chunk of sod from your lawn and count the grubs. Ten or more grubs indicate a need for treatment.

Chemical Controls

The best way to get rid of Japanese beetles with the following chemicals depends on which life stage of the insects you have a preponderance of in your yard. Of course, if you have problems with adult-stage and larval-stage beetles, you will need to use both. Many of these chemicals are found in brand-name pesticides under different names. Be sure to read the label carefully to ensure the formula does, indeed, contain chemicals that kill Japanese beetles.

For adult stage, one of the following:

  • Acephate
  • Carbaryl
  • Cyfluthrin
  • Rotenone
  • Malathion

For larval stage, one of the following:

  • Diazinon
  • Lambda-cyhalothrin
  • Isofenphos
  • Esfenvalerate
  • Chlorpyrifos

Biological Controls

Most biological controls available as the best way to get rid of Japanese beetles work on destroying the insect during its larval or grub stage. Some of these include two varieties of nematodes (only one of which is available commercially), milky spore bacteria (Bacillus popillae), several parasites, and a parasitic wasp (Tiphia vernalis) that lives mainly in the northeastern portions of the U.S. but is also found as far south as North Carolina.

One beneficial insect that does kill adult-stage Japanese beetles is the Istocheta aldrichi. This internal parasite lays its eggs on the thorax of the beetle, whereupon hatching, the larvae bore into the beetle, killing it.

Avoiding plants that attract them may not be the best way to get rid of Japanese beetles, but it does help. Some plants that the insects find desirable include crabapples, Norway and Japanese maples, crape myrtles, pin oaks, birches, roses, and fruit trees including peach, plum, apricot, and cherry.

Plants that do not seem to draw the Japanese beetle include hemlock, ash, boxwood, holly, dogwood, yew, Northern red oak, and juniper. More complete lists of which plants attract and/or repel Japanese beetles can be found online or at your local county extension agents office.

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