NEBRASKA CITY – Grimm’s Gardens hosted a class Thursday to help gardeners and lawn caretakers on the road to victory over the invasive Japanese beetle.

Garden enthusiast Summer Warren led the class on topics of control and deterrence for the beetles.



Warren: “Because they are invasive to America. They can decimate a whole tree or a rose bush in a matter of a day or night.”

They are known to horde together, drawn by sex and food pheromones, and feed voraciously on over 300 types of plants.

She said control methods for adults include:

  • residual sprays that will also kill beneficial insects, such as bees and butterflies.
  • Neem oil is friendlier on bees, but kills the beetles on contact.
  • Remove them by hand and drop them in soapy water

Deterrents include:

  • Plants that repel the beetle are garlic, onion, catnip, chives, white chrysanthemum, marigolds, white geranium and American native tansy.
  • Soak cedar chips in water and spray the solution on plants or around the yard.

Control strategies also extend to different stages of the beetle’s life cycle.


Warren: “When they are grubs or like the larvae, you can use a granular grub control  on your lawn, like in early spring.


The earlier stage of the larvae is the best time to get it under control or you could use “milky spore.”  It takes two to three years for it to be effectively working, but it stays in your yard for 10 to 15 years.”

The bacteria in milky spore is known only to impact the Japanese beetle and is recommended when there is a sufficient population of beetles in the soil to promote growth of the spore.

Beetles that emerge from the soil in June and July are known to travel about 200 yards, but can fly as far as five miles, in search of food and mating opportunities.