Organic Pest Control in Your Garden – Japanese Beetles

| organic gardening

All the lovely Hydrangea are coming into bloom!

The green shiny monsters have landed and they are eating my kale!  Oh my toes curled and I clenched my fists when I went out into the veggie garden last week and saw all the beetle damage that seemed to have crept up overnight.  Darn Japanese Beetles - they can make a gorgeous garden look scraggy and sad in almost no time at all. I rarely kill animals in my garden - preferring to relocate them or simply tolerate their damage - but Japanese Beetles are the exception to that rule.

Japanese Beetles come from grubs in the ground. I'm sure you have heard of grubs.  If not from your local lawn lover then on the radio or at the garden center where you see large bags of product making a big deal of killing grubs.  And their death deserves to be made a big deal of.  They are lousy for the garden and for the lawn. Many of my clients spend a great deal of time and money trying to eradicate grubs, and their control can make the most organically minded person consider (in a brief, mad moment of frustration) just nuking them with pesticides and doing a mini victory dance to celebrate their death.  BUT we all know that the nuking approach won't just kill the grubs - that it will kill all our beneficials as well...and we love earthworms!

So what is an organically minded, earthworm loving girl to do? First thing is to understand where the Japanese Beetles come from and how to eradicate them during all the different stages of their lives.

Right now you are probably seeing these guys in the beetle stage.  They are very pretty iridescent green backed beetles that fly in, group up on plants and begin to feed, leaving the plant veins.  Control at this stage is pretty simple - knock the beetles into bowl of soapy water. It is best to go out and do this early in the morning when the beetles are still wet with morning dew and not able to quickly fly away.  If you want to you can also use a Neem based spray - I recommend the Safer Brand BioNEEM Insecticide.  This needs to be applied frequently  - be sure to follow the directions.

By the way, I do not recommend using the Japanese Beetle traps  - they are usually yellow bags with a hormone soaked piece of fabric/cotton. These do trap lots of the beetles, but research has shown that the traps actually attract more beetles to the garden...and more end up in your plants than would have been there without the traps.  If you do choose to use the traps place them far away from your ornamental/vegetable plants, be sure to empty the bag on a regular basis and replace the hormone strip as directed.

So the Japanese Beetles are killer on your flowers...their grubs are killer on your lawns. The grubs eat the roots of many types of plants, but their favorite seem to be grass roots. Grub damage shows up as irregularly shaped patches of dead or dying grass.  You can also get a pretty good idea of a grub infestation when you are digging up your garden - if you see lots of grubs act quickly!  I squish them or throw them to the ducks to eat.

Here is a handy chart showing the life cycle of the Japanese beetle and one showing what they look like during these phases:

Those grubs gross me out!  But it is important to know what they are.

And now we come to the tough news about treating grubs organically.....there is no magic bullet cure. The best known approach is to infect the grubs and beetles with Milky Spore (Bacillus popilliae), a disease that targets the Japanese Beetle grub and kills it. According to the USDA, milky spore disease can suppress the development of large beetle populations. It is not harmful to beneficial insects, birds, bees, pets or humans and will not  affect wells, ponds or streams. Each time an infected grub dies it decomposes and releases millions of the spores into the environment, creating an accumulative effect over time.  And it does take time - 2 to 4 years. But the treatment lasts for 10 years and is pretty easy to apply.

Some say one application is all that is needed, but I have always followed the classic directions of laying down Milky Spore once in the Spring and again in the Fall for two years. It is a treatment that is expensive in the beginning but pays off over time.

So that is the quick and simple guide to Japanese beetles in your garden....and even quicker guide is to basically say:

Knock the buggers into soapy water, apply Neem to help keep them off your plants, squish the grubs when you see them, introduce milky spore into your yard and encourage your neighbors to do the same.

Sometimes the organic way is a hands on way...and you know what, I kinda prefer that.  As much as I loathe the Japanese beetles, I do find myself out in the garden quite a bit more during their active season...and it really makes me appreciate my plants. And eat my kale!

Next week is more garden pest talk...slugs anyone! Powdery Mildew???!!! We have much to cover.  Until then have a wonderful week and know that your interest in gardening organically is supported and appreciated by this Ladybug!


  • hmmm…I never knew those shiny green bugs were a problem…darn, another thing to worry about! :)

    looking forward to your slug advice!

  • I have an earwig problem and would love advice to stir those creepy little things away from my basil and other plants!

  • I have an earwig problem and would love advice to steer those creepy little things away from my basil and other plants!

  • This is coming at the perfect time! I just went outside yesterday to harvest some of my basil and was utterly freaked out when my plants were covered….just covered….with these little buggers. I had that same angry fist clenching reaction – no one gets between me and my precious basil!! Haha! Thanks again!

  • I had a wonderful yellow rose horribly mutilated by Japanese beetles recently so i understand your plight. I am all for the non chemical/organic approach to gardening and discovered a fabulous cheap home-made concoction a few back to deter deer from eating the “salad bar” or hostas in my garden.
    The recipe is on my blog at

    As with all organic approaches it takes a little effort but this easy to whip up spray really does work.

    Looking forward to your post on slugs, I know they enjoy beer …rather too much, and also remember something about egg shells

  • Hi Kristina, I would recommend diatomaceous earth sprinkled around the base of your basil plants. You can buy diatomaceous earth here:

    Wet the ground first and then apply the powder.

    Don’t use the diatomaceous earth used to keep pools clean, you want one that is specifically for insecticide use.

    You can also use Neem spray. Good luck!

  • Oh Jes! I know…it seems that the more you learn the more work there is to be done! If they beetles are not eating up your precious plants then don’t worry about it!!!

  • Zoe – Thanks for the deer repellent recipe…I’ll have to try it out!

  • Hello Cheryle – I’m so glad to know someone else out there goes through the same fist clenching reaction! Don’t mess with the gardeners of the world!!!

  • Thank you Caroline. Will those options detour other insects, just in case it’s not all an earwig issue?

  • Hi Kristina. The Neem is a pretty effective all round insecticide – the deters a large variety of pests. The diatomaceous earth is also effective on a wide variety of crawling insects. The two should be a pretty good first phase of attack. Remember to wear a mask when applying the diatomaceous earth though!

  • Hi, I read your post about pest control and wanted to mention that I recently launched and have been trying to spread the word. If possible, I would like to discuss helping me out with a link to our new site.

  • A heads-up. Warnings on neem oil products indicate that it also kills our buddies, honeybees. Back to the soapy water!

    • oh, thanks kate! back to soapy water indeed!

  • Last year I noticed that Japanese Beetles did not eat tomato leaves. So this year, I took a cup of loosely packed tomato leaves and boiled them in a quart of water. I let it cool then put the mixture in the blender and whipped it up well. I strained the mixture and added more water-about an equal amount to the mixture I had-and put it in a hand pump sprayer. When the beetles began to appear, I sprayed them and the plants I found them on with the tomato leaf “tea”. It drove away the beetles and repelled any more.

  • Great article! Read more about pest-control on

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