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Japanese Beetle Prevention And Control

Japanese Beetles are an annual problem for many common landscape plants in northern Illinois. Severe infestations can lead to complete defoliation of plants which stresses the plant and in some instances can lead to plant death.

Information

This insect’s larvae overwinters in the soil as a small white grub. In the spring, they will move closer to the surface and begin to feed on small roots of plants like lawn grass. As they mature, they will pupate (change form) into a small beetle with a metallic-like shell. They typically will begin to fly around and feed on plants starting in late June / early July. Their main feeding window is from early July until the end of August. In the fall, the adult insects will tunnel underground and lay their eggs in the soil.

Control

In order to control Japanese Beetle, there are a few things to keep in mind. First, spraying systemic insecticides during the bloom time for plants is not recommended. This can be harmful to pollinator populations. This is the reason that it is NOT recommended to use systemic insecticides on Linden trees, since their bloom time typically coincides with Japanese Beetle Feeding. Plants that bloom during the summer and are commonly attacked by Japanese Beetles should be sprayed with non-systemic insecticides (with active ingredients of Bifenthrin, Lambda or Permethrin) every 10-14 days, to prevent damage to pollinator populations. For spring blooming plants, annual application of a systemic insecticide is the best prevention method for severe Japanese Beetle infestations. Beetle Traps have proven to NOT be effective control measure for Japanese Beetles.
Japanese beetles damaging a Contorted Hazelnut , Image by University of Minnesota

Effective Products

When the Japanese Beetle are present, there are several different products that can be effective against them.

Non-Systemic Insecticides (Shorter efficacy window. Doesn’t get absorbed by the plant.):

  • Hi-Yield’s Bug Blaster (Active Ingredient: Bifenthrin) – Apply every 10-14 days as needed starting at first sign of insect (late-June / early-July)
  • Captain Jack’s Dead Bug Brew (Active Ingredient: Spinosad) – Apply every 7-10 days as needed starting at first sign of insect (late-June / early-July) *Organic*
  • Bonide’s Eight Insect Control (Active Ingredient: Permethrin) – Apply every 7-10 days as needed starting at first sign of insect (late-June / early-July)
  • Bonide’s Japanese Beetle Killer (Active Ingredient: Pyrethrins) – Apply every 2-3 days as needed starting at first sign of insect (late-June / early-July) *Organic*

Systemic Insecticides (Longer lasting. Can take 4-6 weeks to start being effective.):

  • Bonide’s Annual Tree & Shrub Drench (Active Ingredient: Imidacloprid) – Apply once at base of plant in early-mid spring.
  • Bonide’s Systemic Insect Spray (Active Ingredient: Imidacloprid) – Spray on foliage of plant in early-mid spring. (Re-apply every 4-6 weeks as needed)
  • Bonide’s Systemic Insect Control (Active Ingredient: Acephate) – Spray on foliage of plant in mid-late spring. (Re-apply every 4-6 weeks as needed)