Effective protection against Japanese Beetles?

lrobins(z5 CO)September 25, 2004


I am wondering if anyone has found an effective way to discourage Japanese Beetles from feeding on plants that they like? I mean, excluding any of the following methods: "biocontrols" of grubs (see other thread for comments), pheromone traps (counterproductive, increase beetle damage in their vicinity) highly toxic broad-spectrum insecticides such as Sevin (potentially kill beneficial insects), or replacing the vulnerable plants.

My restrictions would appear to leave "horticultural oils" such as Neem oil, and kaolin clay based products (physical barrier against insects, sold under trade name "Surround"), as possibilities. It should be possible to apply the product with a hose sprayer so that a small tree (10 to 15 feet high) can easily be treated.

Plants to be protected include Amelanchier "Autumn Brilliance" (small tree), Oxydendrum arboreum (small tree), Fothergilla "Mt. Airy" (medium shrub) and Clethra alnifolia (small shrub). The JBs go for foliage of the Amelanchier and Fothergilla (which have no flowers when the JBs are active), and flowers of the Clethra and Oxydendrum.

Here is a link that might be useful: Other thread on JB grub biocontrols

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The simpelest way to accomplish this is to grow plants in a good, healthy soil so the plants grow up big and strong and, I guess, don't taste good to the pests so they stay away. Until two years ago when they built on an empty, overgrown lot across the road, I had not seen any Japanese Beetles in my gardens in over 30 years, but now I have them on a few plant species that are under stress, sand cherries, some mallows, a Chinese Elm, but none on the raspberries, roses, or other plants they generally like. Next door has had major problems with them all these years but she uses that popular water soluble "fertilizer" as recommended, while I don't.

    Bookmark   September 25, 2004 at 8:27AM
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Try treating lawns and susceptible flowers with Imidacloprid (merit) early in the season. It is a mild systemic insecticide which is broken down by the soil microbes, but stay affective in the plants and soil for a few months.

If you are sure, that it is the japanese beetle, you can also try milky spores, but they wont work on the grubs of other beetles, such as May or June beetles.

    Bookmark   September 26, 2004 at 4:23PM
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lrobins(z5 CO)

(1) "The simplest way to accomplish this is to grow plants in a good, healthy soil so the plants grow up big and strong." Sorry to be argumentative, but I'm not convinced of that; in other words, the counter-argument is that healthy, strong Japanese beetles will feast on the leaves (and/or flowers) of healthy, strong plants of the types that they prefer. Especially if there's something else to attract them to the area, such as a pheromone "beetle trap". I also (like Kimmer) have used only organic mulches, composts, and fertilizers, since the garden was installed in 2000, absolutely no synthetic or water-soluble fertilizers.

(2) Imadacloprid - I will do some reading about that product, both concerning possible environmental damage (beneficial insects, birds. etc.) and whether it can protect plants against adult, flying Japanese beetles (that will fly in from the surrounding area even if all grubs were eliminated from my lawn and garden space).

(3) "If you are sure that it is the japanese beetle". Yes, I am sure that this is THE problem insect in my garden; no other species shows up in large swarms and devours leaves of not one but many species of plants.

    Bookmark   September 26, 2004 at 7:35PM
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lrobins(z5 CO)

See http://extoxnet.orst.edu/pips/imidaclo.htm

This pesticide cannot be considered "safe" with regard to effect on non-target, beneficial insect species. Note that application on foliage is highly toxic to bees.

>> What happens to imidacloprid in the environment
* Effects on Birds: Imidacloprid is toxic to upland game birds. The LD50 is 152 mg/kg for bobwhite quail, and 31 mg/kg in Japanese quail (223, 1). In studies with red-winged blackbirds and brown-headed cowbirds, it was observed that birds learned to avoid imidacloprid treated seeds after experiencing transitory gastrointestinal distress (retching) and ataxia (loss of coordination). It was concluded that the risk of dietary exposure to birds via treated seeds was minimal. Based on these studies, imidacloprid appears to have potential as a bird repellent seed treatment (332, 333).
* Effects on Aquatic Organisms: The toxicity of imidacloprid to fish is moderately low. The 96-hour LC50 of imidacloprid is 211 mg/l for rainbow trout, 280 mg/l for carp, and 237 mg/l for golden orfe. In tests with the aquatic invertebrate Daphnia, the 48-hour EC50 (effective concentration to cause toxicity in 50% of the test organisms) was 85 mg/l (1). Products containing imidacloprid may be very toxic to aquatic invertebrates.
* Effects on Other Animals (Nontarget species): Imidacloprid is highly toxic to bees if used as a foliar application, especially during flowering, but is not considered a hazard to bees when used as a seed treatment (1). >> ENVIRONMENTAL FATE
* Breakdown of Chemical in Soil and Groundwater: The half-life of imidacloprid in soil is 48-190 days, depending on the amount of ground cover (it breaks down faster in soils with plant ground cover than in fallow soils) (334). Organic material aging may also affect the breakdown rate of imidacloprid. Plots treated with cow manure and allowed to age before sowing showed longer persistence of imidacloprid in soils than in plots where the manure was more recently applied, and not allowed to age (335). Imidacloprid is degraded stepwise to the primary metabolite 6-chloronicotinic acid, which eventually breaks down into carbon dioxide (336). There is generally not a high risk of groundwater contamination with imidacloprid if used as directed. The chemical is moderately soluble, and has moderate binding affinity to organic materials in soils. However, there is a potential for the compound to move through sensitive soil types including porous, gravelly, or cobbly soils, depending on irrigation practices (337).
* Breakdown of Chemical in Surface Water: The half-life in water is much greater than 31 days at pH 5, 7 and 9. No other information was found.

Here is a link that might be useful: Summary of properties and effects of systemic insecticide

    Bookmark   September 26, 2004 at 7:59PM
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lrobins(z5 CO)

Here is the link to the post in the Mid-Atlantic forum about Surround (kaolin clay coating) for protection of plants against insect damage: ""Surround WP presents a unique form of pest control: a non-toxic particle film that places a barrier between the pest and its host plant. The active ingredient is kaolin clay, an edible mineral long used as an anti-caking agent in processed foods, and in such products as toothpaste and Kaopectate."

Here is a link that might be useful: Surround (clay coating) to keep bad bugs away

    Bookmark   September 26, 2004 at 8:36PM
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I also have my doubts about the effectiveness of healthy plants in deterring Japanese beetle attacks. Surviving the attacks, yes; deterring the attacks, no. I'm not saying that what Kimmsr says isn't true in Kimmsr's garden. But, alas, it's not true in my wholly organic, thoroughly composted and mulched garden. I wish it were.

I, personally, me, Alfie, think that a "mild systemic insecticide" is an oxymoron, but this is the IPM forum, not the organic gardening forum, so I'll shut up now.

    Bookmark   September 28, 2004 at 10:30AM
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When we first moved out hewre about 32 years ago I did have a problem with Japanese beetles and did have that problem for a number of years until I got enough organic matter in the soil and the plants started to grow strong and healthy. Until 3 years ago then I saw none, even on the roses and raspberries, but 3 years ago now they cleared a lot across the road and built on it and evidently these JBs have nowhere else to go but on some of my plants, sand cherries, mallows, comfrey, Hibiscus are the only things they were on. None on the roses or the raspberries or anywhere else.

    Bookmark   October 4, 2004 at 7:35AM
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Recent studies (just saw the data at meeting last week) from Purdue show that Neem products do have a repent quality to them. Treated leaves were less likely to be fed on then the control. They are also looking at some systemic effects of neem products.

Also treating for the grub stage right now is another good control practice. Now is the time to treat for next year, when the grubs are very young. This will vary depending on your zone. Beneficial nematodes are my favorite way to treat.


    Bookmark   October 7, 2004 at 1:52AM
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plantfiend(z7 VanBC)

I agree with Buglady. I've had good success with nematodes, but you have to watch the timing of the application. I'm lucky - the place I get them lets me know when the soil temperature is right! You also need some patience as this is not an instant solution. It's taken me almost three years, but I had a bed simply infested with them and they are almost eradicated now.

    Bookmark   October 8, 2004 at 3:46PM
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sandy0225(z5 Indiana)

My daughters bought some chicks for 4-h and two of them turned out to be roosters and they ate every japanese beetle they could reach! They were the best....
I noticed this summer when I planted castor beans, the japanese beetles were dead in piles around the plants and on the leaves. I think they were eating the leaves(poisonous) and dying. anyway, the roosters wouldn't touch those dead beetles. Might need to rethink that old "birdbrain" saying!

    Bookmark   November 17, 2004 at 2:23PM
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lrobins(z5 CO)

Here is some interesting information about Japanese Beetle control from Prof. Daniel A. Potter of the University of Kentucky Department of Agriculture. I have corresponded with this professor, after finding one of his earlier articles about Japanese Beetles on the web, and he has been kind enough to summarize some research results that will probably be published within the next year. I mentioned to Prof. Potter that I would forward his comments to Gardenweb.com.

First, here is my summary: several different "conventional" and organic insecticides and repellents, which are advertised to reduce JB damage to plants, were tested by applying the products to linden tree foliage (one of JB's most favorite foods), "weathering" the treated foliage outdoors for varying time intervals of 1,3,7,14,19 days (to test durability of each product when exposed to the elements including rain), and then offering the treated and "weathered" foliage to JBs.

Some of the more effective products, from longest to shortest lasting, were:
1. Synthetic pyrethroids (deltamethrin, bifenthrin, lambda-cyhalothrin, permethrin, and cyfluthrin): all gave effective protection for more than 19 days. (I don't yet have the trade names in these products, or any information about the "inert" ingredients that are mixed with the pyrethroids.)
2. Sevin: protected for about 14 days
3. "Pyola" from Gardens Alive, natural (botanically derived) pyrethrins in a canola oil base, the most effective organic product: protected for about 5 days
4. "Neem-away" from Gardens Alive, neem oil product, protected for about 2 days

During the protected time span, JBs will not feed (or will not survive an attempt to feed) even when put right next to the "target" foliage. If, as other research suggests, JBs tend to follow a "feeding trail" marked by the pheromone scent of other JBs, it may be that JBs will not return in force to a protected plant (or garden) for some period of time even after the repellent wears off. Such an after-effect was not tested in the study.

Here now is the complete letter from Prof. Potter:
Last summer one of my students evaluated a number of "organic" insecticides, as well as known or putative feeding deterrents for repellence or direct control of adult Japanese beetles on linden foliage. We sprayed individual intact linden shoots, allowed the residues to weather outdoors for varying 1, 3, 7, 14, or 19 d, and then harvested those shoots and challenged them in "no-choice tests" with 10 beetles confined with a treated or untreated leaf, or in "choice tests" wherein 10 beetles are offered a treated versus untreated leaf in an arena. We tested five synthetic pyrethroids (active ingredients were deltamethrin, bifenthrin, lambda-cyhalothrin, permethrin, cyfluthrin) and all of them gave at least 19 days residual control from a single application, despite frequent and heavy rains.

Sevin gave about 2 wks protection (longer than I would have thought), but did not last as long as the pyrethoids. Among the "homeowner-oriented organic products", the most effective were "Pyola" and "Neem-Away", both from Gardens Alive. Pyola is a combo of natural pyrethrins plus canola oil; it was effective out to 3 days, but not to 7 days post-spray. Pyola also was relatively rain-fast once the residues had dried. Pyola served as a feeding deterrent, and also gave rapid knockdown, although most of the exposed beetles eventually recovered in these lab assays. I think they would dessicate and perish in the field. One day old residues of Neem-Away were highly deterrent and gave good protection, but the effect noticeably was wearing off by 3 days, and the product seemed less rain-fast than Pyola.

Surround is a kaolin clay based emulsion that is sprayed on plant material to deter insects. It essentially whitewashes the plant material with a fine film of inert white clay. In our trials, surprisingly it did not deter the beetles from eating the linden foliage. Regardless, I don't think that Surround is well suited to use on roses or other flowering ornamentals because the white coating affects aesthetics. But it does have promise for fruit protection, where the clay residues can be washed from the fruit after harvest. We are also looking at Surround as a borer treatment (i.e., whitewashing tree trunks).

Keep in mind that these were one set of experiments on one plant species (linden), so results might differ on other plants. For example, we did not apply them to open rose blooms. But from what we saw, either Pyola or Neem-Away should give short-term residual protection and be effective if re-applied as-needed (every few days) during the period when Japanese beetles are abundant. Of course, neither will protect rose blooms that break bud and open "in between" sprays. Several of the "natural" plant extract-based products that we tested (and that claim efficacy against Japanese beetles) caused severe phytotoxicity (burned the leaves), so growers would be well advised to test such products on one or two plants before treating a whole garden.

As I am 100% Research and Teaching, I regret that I'm unable to answer all requests from the many individual gardeners who find me on the Web or telephone. We will be publishing this work in both scientific and popular articles, but probably not until sometime later in 2005. Also, we may be doing additional testing on roses. Feel free to follow up later on. Incidentally, there is a good Fact Sheet on Japanese beetle management that can be downloaded for free from the University of Kentucky Department of Entomology website.
Hope that helps.
Dan Potter

    Bookmark   November 25, 2004 at 10:58PM
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Make some spray with crushed garlic and a little dish soap in water. Strain it and spray it. It worked on hibiscus. Does have to be reapplied after rain. Only good for small areas I guess. Don't think you could do a whole tree. (We had six 5' hibiscus plants.

    Bookmark   January 6, 2005 at 2:39PM
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terryboc(z5 NH)

I use Surround on my fruit trees and it worked very well last year. I have plum and cherry trees that JBs love. However, Surround is not attractive, so you won't want to use it on ornamental plants. It leaves a very obvious white film. I have roses that get eaten, but Surround wouldn't be appropriate for them. I hand pick a lot of the bugs. I have used Pyola and other pyrethrin products, but they make me light ill when I spray, so I have discontinued their use. Keep in mind that "natural" or "organic" does NOT mean non-toxic to humans. Use great care when using pyrethrins -they are very toxic.

    Bookmark   February 26, 2005 at 12:02PM
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whitejade(z5 MI)

There's one more thing that can help which I have personally found to be "something" rather than nothing....and that is, to place the plant in the right place. I mean in terms of "feng shui" type energy flow placement. Subtle energy flow dynamics.

Yes, it's also healthy soil, and a healthy plant and good organic practices - but it's more than that too. Definitely. I may not be sure of exactly all the details of this, but I am sure that it makes a difference. I have seen it be a meaningful factor too often over the many years of my acquaintance with plants to logically exclude it.

The insects DO tune into subtle enrgy flow dynamics , it's natural for them. (whereas we tend to deliberately turn away from this entire idea ) When I started tuning into this , boy was I amazed at how much better plants would grow and how good my garden felt overall.... so much so I started making articles on it to post at my website. (one is actually on japanese beetles and roses if anyone is intersted)

    Bookmark   March 15, 2005 at 11:15AM
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The below site has some tips about Japanese beetle control on rose bushes. I have personally found that for roses the soapy water works pretty well. Also, cutting the flowers seems to reduce the number of beetles on the plant :-)

Here is a link that might be useful: http://easyplantcare.com/

    Bookmark   June 26, 2006 at 6:57PM
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username_5(banned for no reason)

So, for those who wish to stay away from broad spectrum insecticides (organic or synthetic) is the 'consensus' that Surround and neem products are the best options?

It goes without saying that the healthier our plants the more natural resistance they will have and the better able they will be to survive an assault, but if we are doing everything we know to do already and they still come, it seems like here and elsewhere these are the 2 products I hear the most favorable things about.

I am fortunate that while there are Japanese Beetles in the area, I only saw 2 in my yard (on sunflowers) last year and squished them without haste. So far they haven't been spotted this year. Hoping my good luck holds out another 50 years or so ;-)

I wish the government would hurry up and import some natural predators from Japan. I know they have to be evaluated for total environmental impact, but still.

    Bookmark   June 26, 2006 at 8:25PM
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I can't believe I haven't seen one beetle yet. Can't explain it. Don't have the huge concentrated display of geraniums I had last year, but I still have a bunch of them spread out.
Are they late this year or am I just lucky?

    Bookmark   June 30, 2006 at 6:29PM
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erdolphin(7 VA)

I've sprayed my nectarine with sevin twice and since then have only the occasional beetle on it. I do go out several times a day with a jar of soapy water and drop them into it. They can survive a long time in just plain water but die within 2 minutes in soapy.

Since I have been hand-picking I have noticed a steep decline in my garden. They love primroses and roses. My neighbor has crepe myrtles and other things they skeletonize. I go to the border of our yards and pick them off her plants because after they mate they drop down to the ground to lay eggs and I don't want them in MY yard! I probably pick off 100+ a day at our border.

I've read that damaged foliage and hoards of beetles both attract more beetles but it seems after a rain they start from scratch and gradually build up again.

    Bookmark   July 31, 2006 at 2:19PM
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I have been amazed to see the evil transformation in my otherwise "I love earth's creatures" personality. I found this discussion on a google search of "KILL japanese beetles". I'm wondering if the FBI has picked up on my KILL search. Thank you for posting your suggestions. I hope that if i can rid of these horrible garden eating monsters i won't miss that euphoric feeling i get when i watch them die.

    Bookmark   August 3, 2006 at 12:24PM
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