Controlling Japanese Beetles

Ozarks Gardening
Copyright 2010 Jim Long

Controlling Both Japanese Beetles and Armadillos!

This summer was my third year of dealing with Japanese beetles. Before that, I had no idea what one even looked like. The first year I had them I bought a Japanese beetle trap and hung it in the garden, and within days, had hordes of the beetles. (Recent research has shown that the traps actually attract more beetles to your yard then you would have normally had; so no more traps for me).


Japanese beetles begin as grub worms. You remember those pesky grubs you found when you were turning over the garden soil last spring? (Several other beetles begin as grubs, too). I feed the grubs to my chickens when I find them in the soil, but I miss a few thousand.

One of the best controls for Japanese beetles is something called Milky Spore Bacteria. It’s a powder that includes a natural bacteria that gets into the bodies of the grubs and gives them disease. They die and their decomposing grub bodies spreads the disease in the soil to more grubs. This bacteria is not harmful to humans, pets, birds or even other kinds of worms, like earthworms - which are beneficial. It only affects the grub worm stage of Japanese beetles.

Milky Spore Bacteria must be applied three times, once in the fall, the following spring, then again the next fall. It’s applied with a simple garden fertilizer spreader and you’ll find the rate of application on the Milky Spore bag; it usually comes in 10 and 20 lb bags.

There is, of course, another method of control, which is to apply a chemical grub killer to your lawn. It does kill the grubs, but you don’t want your pets or children in the grass for several days after the poison is applied. That kind of poison also kills everything else in your soil, including earthworms and over wintering beneficial insects. It often kills birds that eat the poisoned worms, often kills chipmunks, too. And if your cat or dog eats the dead or dying chipmunk, it will probably kill your pet, as well. (You don’t want to kill earthworms, or “fishing worms” as I grew up calling them. They are what keep your soil aerated, help increase the nutrients in the soil and keep the grass roots from becoming compacted).

The safest control is to use Milky Spore Bacteria, If your neighbor’s yard butts up to your lawn, getting them to apply the Bacteria, too, helps even more. Once the three applications of Milky Spore Bacteria has been applied, it remains in the soil for years, continuing to safely control Japanese beetles. Be sure to apply the Bacteria to your garden beds, in addition to the lawn, the sneaky grubs are everywhere.

According to Purdue University, things that have been proven to absolutely not work include the traps, interplanting with supposedly beetle-resistant plants, nor  grinding up the insect bodies and making a spray.

Milky Spore Bacteria is available at many hardware and garden stores (including Nixa Hardware in Nixa, MO). You can easily order it from companies that deliver it to your door. In checking the web, I found varying prices and sizes: Snow Pond Farm Supply Co. Phone 781-878-5581  Biocontrol (800) 441-2847 www.biconet.com and Dirt Works, www.dirtworks.net 877-213-3828. Order yours now and get a jump on next year’s Japanese beetle problem. Oh, and the other benefit of controlling the Japanese beetle grubs? Armadillos, which dig in your yard looking for the grubs, will go over to your neighbors yard and dig there instead!

To see what’s happening in my garden this week: http://jimlongsgarden.blogspot.com. To read past Ozarks Gardening columns from this newspaper, visit: http://ozarksgardening.blogspot.com/ and to see links to additional on-line information. Happy gardening!