Disney and Japanese Beetles

This past weekend I had the opportunity to speak at Epcot Center in Florida.  It was, without a doubt, one of the highlights of my career so far.  I spoke 6 times over the course of 3 days.  The focus of my talk was garden remedies.  I started by talking about Paris Green (a good story for next week), then made fun of some of Jerry Baker’s, Myles Bader’s and Joey Green’s recommendations, and then proceeded to talk about which homemade cures do and don’t work and why.  And then I asked the audience for questions.  I always ask the audience for questions at the end of my talks, but I’ve never had such a diverse audience before (both gardeners and non-gardeners from all across the country), so it was interesting to see which problems came up the most.  The winner was…. Japanese beetle with fire ants and deer coming in a close second and third.  With that in mind I thought I’d devote this column to Japanese beetle control.


Above is my newest prize possession — A statue of Mickey thanking me for speaking at Epcot

The first rule of Japanese beetle control is that you can’t control Japanese beetles.  Nobody has found a sure-fire cure yet and, if you try too hard, you’re going to poison yourself and everyone in your neighborhood.

The second rule of Japanese beetle control is like unto the first.  Don’t trust garden center employees to know a damn thing about Japanese beetle control.

The third rule of Japanese beetle control is not to make the problem worse that it already is.  Using a trap to lure Japanese beetles to their demise will kill a few — and may make you feel like you’re doing something — but you will be attracting more beetles to your yard than you kill.

The fourth rule of Japanese beetle control is that killing grubs doesn’t stop the adults.  In other words, while killing Japanese beetle grubs is possible (usually using imidacloprid), killing those grubs won’t prevent adults from flying into your yard after they’ve hatched from someone else’s yard.

The fifth rule of Japanese beetle control is that Japanese beetle control is dirty work. Most of the "organic" and biological controls just don’t work that well.  If you want to spray a concentrated dish soap spray on the beetles that will kill them, but it won’t last long and it will burn your plants.  Same thing with a spray of one of those citrus insecticides.  The organic insecticide pyrethrum will kill Japanese beetles, but it won’t last long and spinosad (another organic insecticide) which works for some beetles (it’s better on other insects)  just isn’t considered that great.  A biological control called Milky Spore Disease is supposed to kill Japanese beetles while they’re grubs, but the truth is that it usually kills less than 50% even in good conditions.

The sixth rule of Japanese beetle control is that, if you’re willing to go to a little bit of trouble, lose a few leaves, and use a little bit of a synthetic insecticide there is a way to protect your plants to some degree.  If you’ve ever been around these beetles then you’ll know that they prefer some plants over other — for example, they love roses, and so they’ll attack roses first.  If you spray roses with permethrin (a synthetic insecticide) you can get 7-14 days of clean roses, and, if you’re lucky, you’ll kill many of the Japanese beetles before they move on to other plants — this is called trap cropping.

The seventh rule of Japanese beetle control is that these beetles will seek revenge for their dead relatives.

18 thoughts on “Disney and Japanese Beetles

  1. I found the comments about
    620
    Japanese Beetles interesting and mostly on the point. I don’t agree about the use of traps. I have used them effectively in the past when I lived in NJ. Placement is key and they should be away from “favorite” plants. I would empty them several times a week and I had hundreds (at times) with few on my actual plants.

    I also had an infestation of a cousin (Asiatic Beetles) that were killing a butterfly bush back east. I found them easy to stun and pick off at night. Spray with a mild insecticide and then collect them.

    Thanks for the information!

  2. GP Jeff, I have to agree with commenter Jeff. When we lived in western NY, the JBs were horrendous. We set up traps upwind (so the scent passed through our yard from the trap) and emptied the things frequently during beetle season. I can see your point if only a few people used traps, but if most people trapped JBs, that would decrease the numbers of males. Wouldn’t that have a local impact on reproductive output? (I do have to say that handling the plastic bags full of squirming bugs gave me the eebies, and I’m not normally squeamish.)

  3. Jeff and Linda, Good points! First, an increase of Japanese Beetles in one place necessarily means a decrease in another — so if you’ve got a big enough yard (and based on my experiences it would need to be 2 acres or more) you can place the trap on one part to draw the beetles out of another or,
    19e0
    if you live in a smaller lot, you could give the trap to a neighbor who you don’t like. In terms of attracting males, the trap often contains both a sex pheromone and feeding attractants so you may get both sexes. I have heard stories of certain locations, like golf courses, placing traps all over the place and having some success, but I’ve never seen it myself. I just looked it up and there’s a short section on Japanese beetle trapping at this site http://edis.ifas.ufl.edu/in080

  4. I was once a gardener on an historic estate in western Massachusetts, and one of the featured gardens on the property was dedicated to roses. Ambrosia for the Japanese Beetles! We didn’t use any pesticides that I recall. Fortunately for the roses, grapevines growing on a stone wall edging one side of the garden were even more attractive to the beetles. The vines grew like crazy, and I had to prune them pretty frequently — which was fine, and preferable to picking beetles out of roses (though I did do that sometimes, when some decided to vary their diet).

  5. I have had luck using the Bayer tree and shrub product (Imidacloprid) around the base of linden trees to control the beetles on the trees. It did make for a crunchy walk past that tree later on though…

  6. Jeff G. I had to laugh at your comment, “give the trap to a neighbor who you don’t like”, as I use the exact statement in my talks on pest control (as a Master Gardener). While I don’t practice that particular advice, I have had good success in my neighborhood by paying a penny a piece for any JB’s brought to my door by industrious children. It was a pretty expensive endeavor at first, but it gave the kids something to do and helped rid us of the problematic pest. In a nutshell, they can be managed manually by diligent, daily removal.

  7. How effective, if at all, is the cultural method to handpick early ”scouts”, the “first emergers”, who send out feeding signals? The theory being that if you reduce their population, you greatly manage the total population that comes to your property. I’ve also heard that putting one of the traps in an inhospitable tree, like an evergreen, confuses the beetle to try and eat needles that are very difficult for it to digest. These could just be oft-repeated myths with little science behind them.

  8. I found that, like clockwork, July 4th in Massachusetts brought the beetles to decimate my roses. My solution was to grow old roses that bloom once, and gorgeously, in June, and then to resolutely look the other way the rest of the summer.

  9. Dr. Bert Cregg asked me to respond to this discussion of Japanese beetle. Okay, but you asked for it!

    Japanese beetle: top of the gardening most-wanted list

    Japanese beetles strip the leaves of their favorite food plants, turning them into lace. One favorite is little-leaf linden (Tilia cordata), a popular shade tree. They also feed on a wide range of other deciduous trees, shrubs, and flowers, including roses, sassafras, sycamore, pin oak, Norway maple, Japanese maple, pussy willow, birch, elm, canna lilies, raspberries, grapes, beans, Virginia creeper and flowering fruit trees. In Michigan, Japanese beetles continue feeding and laying eggs throughout July and August. By early September the beetles begin to die and few can be found after October 1st. After feeding on leaves and flowers the beetles mate and lay eggs in turfgrass. When the eggs hatch the young larvae become C-shaped white grubs that eat turf roots.
    In order to protect susceptible types of trees, shrubs and flowers from Japanese beetle, spray them with Sevin (carbaryl) or Bayer Multi-Insect Killer (cyfluthrin) as soon as you see the first beetles in late June or early July. Spraying quickly after spotting the beetles is important because other Japanese beetles will be attracted to the wonderful smell of crushed leaves that wafts through the yard when beetles are chewing on the leaves. To them it smells like fresh-baked bread. Spray again every 5 days to 2 weeks, as needed, until late August. Frequent spraying may be necessary, even with highly effective products, because 3 or 4 days after an insecticide has been sprayed, the beetles may feed for a short while before they become sick and leave or die. This is fine for a few beetles, but if a 1,000 beetles visit your plant, you may see feeding damage even if an insecticide is working.
    Carbaryl and cyfluthrin are safe to use, even if sprayed once per week at the labeled rate. They will not damage your plants, and they are not harmful to people if the following steps are followed:
    • Wear gloves when mixing concentrated insecticides into a spray tank, do not spill on your skin or clothes, and don’t breathe the spray powder. The concentrated insecticide before it is diluted may be 100 times more toxic than spray solution. Some products come ready-to-use, and are already diluted.
    • Avoid spraying your skin or clothes, and avoid breathing the spray mist
    • Keep people and pets away from sprayed plants until the spray dries.
    • Do not spray edible garden plants unless the insecticide label gives information how many days to wait after spraying before washing and eating the fruit or vegetables.
    • Try not not mix more insecticide than what you will use when spraying. Any left-over spray should be sprayed on your trees, shrubs, turfgrass, or other plants listed on the label.
    • Store pesticides in a place safe from children. Most pesticide poisonings result from the accidental ingestion of a pesticide.

    Japanese beetle traps are a double-edged sword. They are highly effective in attracting beetles, pulling them in from 1/4-mile away. They also trap and kill up to 10,000 beetles in one trap. The problem is that they may attract more beetles than they kill, causing a spill-over effect that may result in more damage to your plants than if you didn’t use them at all. In a study in Kentucky by Dr. Dan Potter, trees and shrubs were more likely to be defoliated if a Japanese beetle trap was placed nearby.

    If you woud like a formatted version of this, or a 4-page summary of recent work on biological control of Japanese beetle, let me know at smitley@msu.edu

  10. I’ve found neem oil to work surprisingly well for Japanese beetles. I’ve noticed it won’t kill them, but will repel them. It’s the most and perhaps only (in my opinion) effective use of neem oil I’ve seen. Imidacloprid works when applied before beetles begin feeding. They now have Safari available to homeowners and I hear that has quicker translaminar movement but it won’t last as long as Merit inside the plant.

  11. @DeViouSsSs, thanks for the heads up about the spam posting. Somehow I missed that one. But it’s history now.

  12. Hi!
    I have a quick question, if I may?

    To crush, or not to crush?
    I’ve read that if you crush them, they emit all their pheromone at once, drawing in more beetles. Yet I also read where folks are putting JB in the blender, straining the resulting liquid, and using it as a spray “deterrent” on their plants. I am skeptical that both can be correct, so, please advise?

  13. @Dea, Jeff Gillman is in the process of moving to North Carolina. I’m sure he will get back to you once he’s settled.

  14. I go out 2 to 3 times a day with a bucket of soapy water in my have and vengence in my heart. They currently plague our ferns, raspberries, green beans, a cherry bush and occassionally land on some of the flowers. Due to the height of the cherry bush, I was failing at getting a number of them so I finally made myself a butterfly net to get some extra reach and to nab the ones that took flight. Being vigilant has cut down on the number in our yard and a neighbors yard. We put out milky spore this spring (first year so I don’t expect much). I derive far too much pleasure from drowning the little buggers.

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