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Japanese beetles on a pussy willow bush. When they get angry, they lift their rear legs as a show of force.

While checking properties today in Minneapolis, I noticed that our friend the Japanese Beetle has arrived in Central Minnesota.

Japanese beetles are nasty buggers that are merely nuisances on light years and can completely defoliate a tree on bad ones. Generally, the infestations in the Upper Midwest are not bad enough to require much pesticide application. However, they can get bad over a period of years and require treatments to kill them.

Here’s a video I took of Japanese Beetles a few years ago.

Killing Japanese Beetles

Beetles

If you have a lot of beetles in one area, it doesn’t necessarily mean you have a problem. They fly a long way to get to their food sources and can fly back there to lay eggs.

If the beetles are particularly bad, you can spray them with an insecticide – make sure to call a professional. A few don’t constitute a problem.

When you have beetle infestation recurring each year on a property, that is when you need to look at the ground.

Japanese Beetle Life Cycle

Japanese Beetle Life Cycle

Scouting for Grubs

Japanese Beetle grubs lurking just below the surface

Grubs are the larval stage of many different types of beetle. The grubs of Japanese Beetles are – not surprisingly – fairly intense when you get a lot of them.

If you truly do have a grub problem – you’ll see one or more of these on your property:

  • small, dead patches of turf
  • birds on your turf (they’ll know before you do)
  • areas of turf peeled back by raccoons (again – they’ll know before you do)

In order to see if the cause of the dead grass is grubs, you will be able to take a handful of grass and peel it back like a rug. Grubs chew off the turfgrass’s roots and completely separate the plant from the soil.

Treatment

On commercial properties, you need to call a professional that has a pesticide applicator license in order to apply any restricted insecticides (which are usually necessary here).

You’ll pay a few hundred dollars but ONLY apply if you can physically see the grubs. If you miss the window where the grubs are actively feeding, it will do you no good and waste the chemical and money.

Resources

Japanese Beetle Management in Minnesota
UMASS Japanese Beetle Resource
Original ELC post on Japanese Beetles