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Pyrethroid is the sole tool against Japanese beetles

Pyrethroid insecticide is the recommended tool for crop farmers dealing with Japanese beetles.

“Right now, we do have established thresholds for corn and for soybeans that we recommend. The best thing you can do is scout your fields, count the number of beetles and look at the damage and if you hit threshold then use an insecticidal spray.”

Kevin Rice, with the University of Missouri Extension says insecticide must be sprayed multiple times, in most cases, to get rid of new groups of beetles but must be used sparingly since it can also kill off crop pollinators.

Rice and his team are doing research on an insecticidal netting that catches Japanese beetles.

“These nets are probably not going to be a silver bullet for Japanese beetles, but it is a bullet and it may reduce some of the application during the season.”

The netting is not yet available for growers since research is still being done. He hopes to have results by the end of this year. Rice says natural predators that help control populations East of the Mississippi River have not migrated to Missouri and states west of the river where the beetles have shown up in recent years.