Japanese Beetle – Chalet

The Japanese beetle was found in New Jersey in 1916. Since then it has spread throughout the eastern US. About the size of a fingernail, the iridescent roundish beetle is easily recognized by its brown body and green head. In the larval stage the beetle lives as a grub in lawns, feeding on roots. The grub emerges as a beetle in early July then flies to trees and shrubs to begin feeding. Beetles live for 30-45 days.

DAMAGE

Both grubs and beetles can seriously injure plants. The roots of turf grasses seem to be the food of choice for grubs; beetles feed on nearly 300 species of plants, roses being a particular favorite. On tree leaves beetles devour the tissue between the veins, leaving a lacy skeleton. They are most active during the warmest part of the day and prefer to feed on plants that are fully exposed to the sun. Other preferred plants include crabapple, cherry, elm, Japanese maple, linden, weigela and viburnum. Beetles have not been seen feeding on dogwood, forsythia, holly or lilac.

CONTROL

The best control for beetles is systemic insecticides.

Bayer Rose & Flower Insect Killer – 30 day control, ready-to-use spray
Bonide Systemic Insect – 8 week control, granular
Bayer Tree & Shrub Insect Control – 1 year control, drench. Apply to soil 30-60 days before beetle feeding begins

Earth-Friendly Natural products are great for those who prefer non-chemical control.

Captain Jack’s Deadbug is a selective bacteria that has minimal impact on desirable insects. Apply to both upper and lower leaf surfaces at 7-10 day intervals when insects are feeding.
Bonide Insecticidal Soap is effective when applied directly to the beetles every 3-5 days.
Espoma Earth Tone Insect Control contains pyrethrin with canola oil and is effective when applied directly to the beetles every 7-10 days.

To control the larval or grub stage of the beetle it’s best to apply a preventative insecticide to the lawn in May or July. Scott’s Grubex or Bayer’s Season Long Grub Control are absorbed into the turf’s roots and stay in the plant for 8-10 weeks. When the grubs hatch and begin eating the roots of the turf they get killed. Use Bayer 24-hour Grub Control with Dylox if grubs are present and a preventative control was not used.