Japanese Beetles Diagnostic Guide
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.
Trees at Risk
Japanese beetles feed on a number of common shade trees, shrubs, woody ornamentals, fruit and vegetable plants. Japanese beetles attack over 300 species including: linden, crape myrtle, flowering crabapple, Norway maple, Japanese maple, flowering cherry, elm, sycamore, black walnut, horse chestnut, plum and gray birch.
Signs of Damage
Individual leaves are missing leaf tissue between the leaf veins causing a lace-like skeleton appearance.
- Adults are 3/8 “ long with a metallic green head and thorax, and copper-brown wing covers.
- Adult beetle have a row of five white hair tufts projecting from under each wing cover and two more at the rear tip of the abdomen.
- Larvae are white, C-shaped grubs 1/16 “ – 1/4”. These grubs can be significant turf pests.
Soil applications of Xytect™ or Lepitect™ will provide acceptable levels of stand-alone control. However, if there exists a low threshold for leaf damage or if infestations are high, consider combining soil applications with a foliar spray tank mix of Xytect™ and Tengard™ during adult flight period (July-August). Spray treatments are required once adult feeding occurs on trees that have not been treated preventively. Tank mixes of Xytect™ and Tengard™ will provide a high level of control for 14-21 days. Sprays should begin at the early onset of adult feeding. Protecting trees against the early feeding is extremely important. Japanese beetles are attracted to trees that are being fed on by other beetles, so keeping them from feeding initially is important.
*NOTE: Do not apply Xytect 2F in the state of Oregon, by any application method, to linden, basswood or other Tilia species.
Soil Application using Xytect 2F
Dosage: 6 mL/in DBH Timing: Late fall or Early spring Re-Treatment: AnnualXytect 2F$69.60
Soil Application using Lepitect
Dosage: 0.2 - 0.4 oz/in DBH Timing: Early June to provide protection into August. Re-Treatment: AnnualLepitect$59.20
Foliar Spray using Xytect 2F
Dosage: 1.5 oz Xytect™*/100 gal water + 8 oz Tengard™ Timing: When beetles are present. Re-Treatment: Reapply at 14-21 day intervalsXytect 2F$69.60
When the soil applied systemic products Xytect™ or Lepitect™ are used, the beetles may continue to feed, but they die soon after. 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 soil applications with foliar spray applications for those with low tolerance for leaf damage or in areas that have a history of severe infestations. Feeding adult beetles attract more adult beetles to attack.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org