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GLT's Grow: Combating Japanese Beetles With Milky Spore

David Hill
Flickr via Creative Commons
Milky spore can be an effective treatment against Japanese Beetles.

Japanese Beetles are the bane of every gardener. These voracious insects are tough to get rid of, but can milky spore come to the rescue?

  • If you've got Japanese beetles, you've got grubs—nasty wriggling little grubs all through your lawn.
  • They're the next generation of Japanese Beetles, just percolating away beneath your lawn until the day comes that they emerge and chomp their way through the tastiest bits of your garden.
  • Milky spore is one way to combat these critters. But it takes patience.
  • Treat your lawn with milky spore and the bacterium Paenibacillus papillae will go to work on the grubs under the grass. But it will do so slowly, over time. So, yes, you may have to put up with the grubs emerging as adults to defoliate your trees for a year or two, but faithful applications of milky spore will pay off down the road.
  • Use a teaspoon of milky spore powder on the lawn, spacing the applications about four feet apart.  You'll be forming a grid to make sure you cover the lawn effectively. Carefully water it in with a gentle spray from a hose. Once you've incorporated the powder, you can safely mow or walk on the lawn. 
  • Apply in the summer and the fall, when the grubs are actively feeding. Good control happens within one to three years. 
  • You won't kill all the grubs in your lawn, but you'll make a healthy dent in them with milky spore.

GLT's Grow is your source for sage gardening advice and down-to-earth tips. Host Patrick Murphy and co-host Laura Kennedy are ready to take on all your gardening questions, so submit yours today.

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Reporter, content producer and former All Things Considered host, Laura Kennedy is a native of the Midwest who occasionally affects an English accent just for the heck of it. Related to two U.S. presidents, Kennedy appalled her family by going into show business.