Native to Japan, the Japanese beetle (Popilia japonica)was first detected in New Jersey in about 1916.  It has since spread to nearly every state East of the Mississippi, and continues to spread each year. 

The adult beetles are skeletonizers, which means they feed on the leaves of trees by eating the tissue between the leaf veins.  Severe Japanese beetle infestations can completely devour all of the tree’s leaf tissue, leaving only the veins behind.  They will often feed on flowers and fruit as well. 

Susceptible Hosts
* Japanese beetles attack over 400 species of plants including many trees and shrubs such as linden, crape myrtle, flowering crabapple, Norway maple, Japanese maple, flowering cherry, elm, sycamore, black walnut, horse chestnut, plum, gray birch, and others.

Pest

Popilia japonica

Symptoms
* Individual leaves are missing leaf tissue between the leaf veins causing a lacelike skeleton appearance
* After being “skeletonized”, the leaves soon wilt and die
* From a distance, severely attacked trees appear as if they have been scorched by fire

Signs
* The adult is a 3/8 inch (8-11 mm) long beetle with a metallic green head and thorax, and copper-brown wing covers.
* The adult beetle has a row of five white hair tufts projecting from under each wing cover and two more at the rear tip of the abdomen.  This characteristic distinguishes Japanese beetles from other beetles with similar color traits.  
* The larvae are white, C-shaped grubs about 1/16 inch (1.5mm) at first instar.  At maturity, the larvae are 1 ¼ inch (32 mm).  These grubs can be significant turf pests.

Life Cycle
* The larvae overwinter in the soil at a depth of 4-8 inches
* Adult emergence occurs over a 3-4 week period during late June through August.  Upon emergence, adults release pheromones that attract other beetles.
* After mating and feeding on leaf tissue for a couple days, the females lay 1- 5 eggs into the soil and return to the tree to start the feeding, mating, and egg laying cycle over again.  The females will lay about 40-60 by the end of these cycles.
* The eggs hatch in 8-14 days where the larvae feed on roots and organic material before overwintering.

Distinguish from Look-alikes
If the beetle does not have a row of five white hair tufts projecting from under each wing cover and two more at the rear tip of the abdomen it is not Japanese beetle.

Apply Xytect soil applications in late fall or early spring

Lepitect and Transtect should be applied in early June 3-4 weeks prior to adult emergence in early July.

Up-Star EC TT&O foliar sprays should be made when adult beetles begin to damage plants (900-1200 GDD). 

Re-treatments:
Apply Xytect and Transtect treatments annually.
A second soil application of Lepitect can be considered 30 days after the first application. 
Up-Star EC TT&O foliar sprays may have to be applied every 10-14 days throughout July and August.

Expectations:

* When only Xytect or Transtect is applied, the beetles are not prevented from feeding, but they do die after they feed, some defoliation should be expected even on treated trees.  From a distance trees will look fine, when viewed close-up you will see some damage.

* Combine Xytect and Transtect with soil applications of Lepitect or foliar spray applications of Up-Star EC TT&O for clients with low tolerance for leaf damage or in areas that have a history for severe infestations.  Lepitect soil applications can be applied in the early stages of the adult feeding period to provide additional control in combination to Xytect or Transtect soil applications.

* Feeding adult beetles attract more adult beetles to attack.  

Other Treatment Practices:
* Hand picking the first adults to arrive on a property and dropping them into a container of soapy water can be effective when populations are low.  The presence of beetles on a plant attracts more beetles.

* Plant trees that are less attractive to the Japanese beetle such as American elder, arborvitae, black oak, boxelder, fir, green ash, hemlock, pine, red maple, oak species, silver maple, spruce, white ash, and white poplar.

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