Japanese Beetle Deterrents

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The Japanese Beetle, Popillia Japonica, is a voracious garden pest with the potential to cause extensive damage to landscapes.  Common throughout most of the Eastern United States, it can damage turf grasses, shrubs and trees.  Fortunately, there are environmental and man-made deterrents and controls at our disposal.

Background and Information

Location: The Japanese beetle is common throughout the state of Virginia.  They were first found in a New Jersey nursery in 1916 and have since spread to the majority of the Eastern United states.

Description: The adult Japanese beetle is bright metallic green and is about (.06) inches long and (.04) inches wide.  Smaller than the Green June beetle, the Japanese beetle wing covers are copper colored with layers of white hairs on the abdomen.  Males display a sharp spine and  females display a rounded spine.

Lifespan:  Adult Japanese beetles begin emerging from the ground about late-June and most are out by mid-July.  Shortly afterward, males and females begin to mate; females then dig burrows into the soil to lay eggs until mid-August.  Eggs hatch within 8-9 days of being laid.  Starting out as a grub, they feed and develop as the soil begins to cool into the fall season at which point they burrow deeper and stop feeding.  Grubs will reach full size in late-May and pupate.  Adult beetles emerge weeks later thus completing the cycle.

Feeding habits and Damage

Feeding: Due to feeding habits, they can severely damage fruit trees and grapes and be difficult to manage on vegetable gardens and field crops.  The Japanese Beetle also feeds on a wide variety of trees, shrubs and herbaceous plants.  At immaturity, known as a grub or white grub, they can also be quite pesky on many grasses grown for turf in Virginia.  In fact, this species is not harmful in Japan because of natural predators, but in Virginia, it is a serious pest to over 200 species of plants.

Damaged  tree symptoms: Japanese Beetles chew holes in leaf veins giving leaves a lacy appearance called skeletonizing.  Damaged trees and plants may take on a brownish cast as leaves shrivel and die.

Damaged turf symptoms: The immature Japanese beetle, or grub, feeds just below the soil surface on roots and lower plant sections.  This may cause damaged turf.  The most common symptom of turf damage is discoloration.

Pest Control

Dry conditions (biological): Dry conditions in late July and early August will cause poor establishment and reduce populations for the following year.

Milky Spore disease (biological):  Milky Spore disease is a control option developed by the USDA and available in powder form for use on turf.  It may take (1) to (5) years to maximize protection, during which no pesticides may be used.

Insecticide (chemical):  For turf, apply a registered insecticide in early August when grubs are small and before damage becomes extensive.  Applications may be applied during other times of the year but will be much less effective.

Systemic insecticide (chemical) :  For ornamental trees, shrubs, and herbaceous plants, systemic insecticides may be applied.


If you need assistance with Japanese beetle pest control (or any pest control), please contact our office at (434) 973-1154 or e-mail jwt@townsendlandscape.com.





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