Japanese Beetles 2018—Preparing for the Onslaught

Gardeners, plant aficionados and tree owners are battening down the hatches for the onslaught of Japanese beetles this growing season.  Here are some commonsense ideas for dealing with these voracious eaters.

First, control measures for Japanese beetle (JB) grubs in the soil will help minimize damage to the turfgrass but does not create a force field of protection for your rose, linden tree or other plants in your yard. JB adults can still fly in from other areas to eat your plants.

Next, consider a systemic insecticide containing the active ingredient imidacloprid for your non-edible plants like roses.  This product is not legal to use on linden trees, so opt instead for your tree service to apply insecticides containing the active ingredients bifenthrin or chlorantraniliprole.

Be aware that applying insecticides to the flowers of plants is going to kill pollinators too. Hand-picking JB from the flowers, usually around 7:00 in the evening, will keep their numbers down overall.

For edibles such as peaches, insecticides labeled for use on edible crops will need to be repeated and even then might not keep the JB numbers down to the point where no damage is done to fruits and vegetables. Bagging individual fruits with paper or fine mesh bags will provide protection without the application of an insecticide.

Japanese beetle traps are too good at attracting JB to your property.  Studies indicate a higher number of JB in yards, feasting on your plants, with the traps than those yards without the traps.

More information can be found here: https://extension.unl.edu/statewide/douglas-sarpy/pdfs/ce/resources/ce-dealing-with-japanese-beetle.pdf .

Kathleen Cue
Horticulture Educator at Nebraska Extension
Kathleen serves as the Horticulture Educator for Nebraska Extension in Dodge County. She educates people on making smart plant choices to reduce use of fertilizers and pesticides in their landscape which has a positive impact on air, water, soil and environmental quality, property values and people’s pocketbooks.

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