Condo Blues: 4 Natural Ways to Kill Japanese Beetles

Friday, August 22, 2008

4 Natural Ways to Kill Japanese Beetles

Last summer, after losing several bushes in my front yard to grubs I tried to plant a grub resistant garden. This summer, I thought that I had the grub problem licked. I was wrong. I still had grubs in my soil. The grubs grew up to become adult Japanese beetles. The Japanese beetles started to munch on my new plants.

I may have lost that battle but I am determined to win The War on Grubs and Japanese Beetles. In addition, for the sake of my dog Blitzkrieg and his habit of walking through my garden bed, I’m going to kill those grubs and Japanese beetles using natural and organic methods even if it kills me (which it just might.)

According to Gardens Alive
insect problems are always worse in non-organic gardens, where the balance of nature is out of whack. Chemical fertilizers cause lush, weak growth that brings in pests by the droves. And, as many listeners wrote when telling us about their beetle woes, toxic chemical pesticides like Sevin don’t work well to control
these (and other) pests, but are excellent at killing and driving off beneficial
insects, birds and other predators that DO—not to mention limiting your happy
and healthy lifespan on the planet

Four Methods for Killing Japanese Beetles in the Garden

That validates my desire for killing these pests naturally. Unfortunately, for me and my I-want-to-fix-the-problem-now desires, the best way to treat my soil for grubs is not the quick fix solution but to use a multi step long term fix. I should:

Step 1. Trap the bugs.
Step 2. Treat the plants.
Step 3. Remove diseased plants & plants that attract Japanese beetles.
Step 4. Treat the soil for grubs and beetles.

Step 1. Use a Japanese Beetle Traps
  • DIY beetle trap Fill a yellow container (I used an empty yellow margarine tub) with water and add a few drops of dish soap. Place the trap next to the Japanese beetle infested plants. The yellow container draws the beetles over to investigate, where they eventually drown in the water because they are lousy swimmers. I tried this method and it works.
  • Buy a bettle trap (here) baited with a pheromone that draws lonely Japanese beetles looking for a little beetle love into the Japanese beetle trap. recommends that you use one trap per every 50 feet of property. They also recommend that you put the beetle trap at least 10 feet away from your plants or the trap may attract beetles to your plants instead of away from your plants. Apparently Japanese beetles really like sex, because those little suckers fill up fast.
Step 2. Using Natural and Organic Plant Sprays to Treat Plants for Japanese Beetles

If you want to try to save your plants, you may try spraying them with something that will make your plants less tasty to adult Japanese Beetles.

  • Spray your plants with Neem oil. Neem oil comes from the neem tree and is available at garden centers (I couldn't find it locally but found neem oil for sale on Amazon here.) It is safe around pets and children however; you must reapply the spray every few days.
  • Make Homemade Japanese Beetle Spray #1 by liquefying dead Japanese beetles in a blender and spraying the stinky concoction on your plants. Again, you must reapply the spray every few days. Also? Ew.
  • If spraying stinky beetle juice on your plants doesn't have much appeal try Homemade Japanese Beetle Spray #2. Mix water, garlic cloves, and a hot pepper in a blender, strain the garlic and pepper out the mixture, add a few drops of dish detergent, and spray on your plants. You must reapply the spray every few days, especially after it rains.
My plants were too far gone to try the sprays. I had to move on the something a little more drastic.

Step 3. Removing Diseased Plants & Plants That Attract Japanese Beetles From the Garden

According to suite101,
diseased plants and trees can attract Japanese Beetles to yard where they
feast on the dying plants and then move on to the healthy plants
After checking the condition of the plants in my yard and removing the affenders, it’s no wonder that the grubs and Japanese beetles considered my yard a smorgasbord:
  • Last year I planted Delilahs. This was pretty stupid on my part because I know now Delilahs can attract Japanese Beetles that lay eggs, that turn into grubs, that grow up to be Japanese Beetles and lay more eggs. I’m kicking myself for this one.
  • The Japonica Spirea bushes that I tried to nurse back to health from last summer contracted bad case of spider mites and other ills that caused black spot and yellow leaves.

  • The roots of the lone holly bush were covered in grub eggs and slime mold. Side note: slime mold smells awful!
  • The Chrysanthemums and Asters (all grub resistant plants by the way) were covered in white leaf mold. That means that not only am I fighting grubs and beetles but my soil is also infested with mold and fungus gnats. Great.
After I removed all of the infected plants from my garden, which was in essence all of the plants I had planted in my garden bed. It is now disease-free. It also looks like something out of Mobile Home Disaster. However, I’m not planting any new plants until I treat the soil.

Step 4. Treating the Garden Soil and Lawn for Grubs and Japanese Beetles

Gardens Alive suggests that I stop watering the lawn and let the grass go dormant in order to discourage Japanese beetles from using my yard as a party pad and later a nursery for their offspring. They say:
"Female Japanese beetles only lay their eggs in turf, and you can cut the numbers of the resulting grub babies that reside in YOUR lawn substantially… don’t scalp your lawn or water it during dry spells this summer; those females will soon be egg laying, and they greatly prefer moist, low-cut turf. (Don’t worry if rain is scarce; the lawn will just go dormant and green up again when wet times return, but those females will have long since flown to homes where they have a fast hand with the hose.)"
This one’s easy and well, frankly, I’m not very good at remembering to water the lawn anyway. This method is perfect for me!

Next, I need to so something about the grubs and grub eggs that are currently in my garden soil. I bought and applied Milky Spore powder (again from my BFF Amazon here.) Milky Spore an organic bacterium that multiplies in the soil over time, attacks the grubs, and kills them. This method is safe to use around pets and children. This is the only thing I applied to my garden that killed the grub eggs in the soil. Milky Spore is on the expensive side but it was worth it because I don't want to replace the landscaping again because grubs and beetles killed my plants.

If you don't want to use Milky Spore you can apply beneficial nematodes to the soil. (Again Amazon sells it here.) Beneficial nematode work the same way as Milky Spore however beneficial nematodes are live insects.

Like Milky Spore, beneficial nematodes can be used around pets and children and they do not target the helpful bugs and worms that inhabit your soil. The downside to using beneficial nematodes is that they do not multiply in your soil like Milky Spore– their lifespan is generally 18 months. Beneficial nematodes are also expensive but they also combat other garden nasties like fungus gnats as well as grubs. Most gardening experts suggest that applying a combination of Milky Spore and beneficial nematodes is one of the best ways to rid your soil of grubs and grub eggs.

Since I have a whole host of bad garden bugs in my garden, I’m using beneficial nematodes and the Milky Spore to kill the grubs and beetles in my yard.

There you have it. My four step approach to riding my lawn and garden of grubs and Japanese Beetles. Do you have a grubs and Japanese Beetles problem in your lawn or garden? What methods did try to fight them that worked for you? What methods didn’t work for you?

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Anonymous said...

I have had minor problems with Grubs and bigger issues with the beetles themselves. I have used the traps in the past and have considered Milky Spores but haven't gone that way due to the cost. I did apply a chemical from Bayer that was an all season long grub killer. Believe it or not I have not seen ANY beetles yet. Could it be that simple? I hope so. In previous years I have just sprayed the trees when they started to munch and used traps. I would loose about 20% of the foliage but the tree survived and I trapped a bunch of beetles. I'm hoping that the Bayer killer worked and I wont need to spray the tree this year. Maybe the things are just hatching later around here this year.

AmazinAlison said...

Ha ha! I almost didn't read the post because of the title, I thought it would be boring, plus I don't know what Japanese beetles are -- perhaps we don't have them in arid Colorado? Nonetheless this post cracked me up (as your writing often does) and it is an inspiration to all of us and with various insect problems to keep trying. We recently had a boroughing wasp issue that my husband's been prodding me to write about...maybe I will now!

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Lisa Nelsen-Woods said...

green me - according to my research, Japanese Beetles aren't in Colorado. Since you're a good blogging friend, I'll be nice and wont' send you any. Thanks for the compliment. Readers, follow Green Me's example and read all of my posts. Every. Single. One. I'll be glad you did.

Handyguys - I used the Bayer killer last season because it was too late in the year to use Milk Spore. I think it didn't work for me because I replanted some plants that I didn't fully de-grub egg as well as I thought.

Anonymous said...

Well I stopped watering my lawn for the most part this year and have let it get longer (read: more natural/I like being lazy) as well. Haven't noticed any Japanese beetles this year, perhaps there's the reason! Last year they destroyed my roses so bad that I gave up on roses, maybe next year I could try again? I sprayed those Japanese suckers with Sevin and they'd just look up at me funny and crawl away, irritated but very much not-dead. Who'd've thought that just letting the grass get longer was all the weapons I needed?

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