Japanese beetles

chuck60July 11, 2011

We had a bad outbreak of Japanese beetles last year and I swore I would put down milky spore to try to get ahead of them. Of course I did not do that. So, this year the JBs are even worse. I have four traps out and have been emptying the bags for re-use. I must have collected a few gallons of JBs so far. I'm using the traps with the hour-glass shaped plastic bags made by Spectracide. Sometimes the bags have been full all the way to the bottom of the plastic holder. Two of those fills a plastic grocery sack, which I then knot and throw in the trash. Trash is getting REALLY stinky.

I had one of the plastic holders from last year, but no extra bait, so I put some cloves in a baggie and smashed them a bit, which also made small holes in the baggie. That works as an attractant because the main ingredient in the bait is eugenol, which is the principal essential oil of cloves. It isn't as effective as the commercial bait, but it does work.

Yesterday I bought a 20lb bag of the spreadable milky spore and will spread it this week. I'm hoping we will get rain in a couple of days, and my plan is to spread it the evening before a rain if possible. Where I will spread it is too far from my water and I think you are supposed to water it in after spreading. Anyway, I'll be treating this week and again in the fall, and then again in the spring. Hopefully that will help. Anyone know of a use for several pounds of dead Japanese beetles?


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I believe it takes a couple years for the milky spore to spread before you will notice a great decrease in the JB population. So next year you might still have quite a few.

We spread the spore about 8 years ago and are still in the period where the JBs are quite minimal. I think it lasts about 10 years before you must re-apply, so we're expecting to see an increase in JBs in the next couple years.

I had alot of JBs the first several seasons after spreading milky spore.

    Bookmark   July 12, 2011 at 6:09AM
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Those "traps" were originally used to see if there were any Japanese Beetles in an area, they help attract them.
Miky Spore Disease, "Bacillus popilleae", is a passive method of control and requires that the grubs ingest some for it to work, so it can take some time. One nice thing about it though is each infected grub spreads the spores around more. Some studies indicate you may need to add more in about 20 years. Spreading the MSD around your yard can help reduce the population some, in your yard, but any from untreated areas further afield will come in where there is a food source and other beetles to mate with.
Going out early in the day, while those adults are still sluggish, with a bucket of soapy water to knock the wee buggers into helps reduce the population.
Careful use of broad spectrum poisons such as Neem Oil or pyrethrin based products has helped, although since the life span of these beetles is fairly short they will soon be gone anyway.

    Bookmark   July 12, 2011 at 6:46AM
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rhizo_1 (North AL) zone 7

chuck, with 4 beetle traps, you are very successfully attracting all of the beetles in the neighborhood to your yard! You'd be far better off disposing of the traps (unless you can talk an unsuspecting neighbor into using them) and going with the milky spore.

I've found that the neem really helps; you might try that on your adult population. Neem has very little effect as a broad spectrum insecticide, but acts on those insects that feed on the plant. Once ingested, it acts as a growth regulator. Neem also acts as something of a repellent...a pest insect may decide not to feed or lay their eggs on a treated plant. So, apply the neem to your favorite JB plants and see if you notice an improvement. Spray the foliage, not the beetles. It won't do anything to the beetles if you spray them.

    Bookmark   July 12, 2011 at 11:35AM
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My nearest neighbors are far enough away that I am probably seeing my own JBs, though I may well be attracting them from distant areas of my own property. I had them on apple and plum trees, so I sprayed those with liquid Sevin. I am fully aware of the potential problems with Sevin, but it is very effective against JBs and seems to function as an anti-feedant in addition to killing them. As many of my apple trees are in their first, second or third leaf, I am mainly interested in keeping them alive and growing and not in protecting any fruit they may produce this year.

So far, the traps seem to be keeping the JBs off my garden. They were on my pole beans early on, and they got the Sevin treatment there, but since I now have flowers and beans it is up to the traps to keep them occupied, and that seems to be working. I will know by tomorrow if the numbers in the traps are decreasing. Some folks in my area are seeing a slow decrease, so perhaps they are about to finish their run. However, I expect that if we get rain I may see some more emerge.

Hand picking these things may work for small infestations, but my DW will tell you we don't have a small infestation. There are two flowering plums in our back yard which I had not sprayed. DW was out there and saw a dead limb on one she wished to remove. As soon as she tugged on that branch a cloud of JBs fell on her. Her distress signal was quite impressive and drew me to the rescue from a distant corner of the orchard. I think she would have approved my use of a flame thrower at that point.


    Bookmark   July 12, 2011 at 1:01PM
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rhizo_1 (North AL) zone 7

AAhhh...fruit trees! That sheds a different light on things. Have you heard of a product called 'Surround'? It's a kaolin clay barrier, formulated to be applied in a slurry that can be sprayed on your trees, and vegetables, for that matter. It works great to keep feeding insects away from your valuable crops. Spray it not only on the leaves, but the actual fruit and veggies. You'll want to apply two or three coats for best results. With the JBs, you'll probably only have to do this once per season, though.

I use it in the veggie garden for more than the beetles. It works to keep pests from feeding on the plants and from laying their eggs. Avoid spraying flowers.

Do some research on the Surround. It's a favorite amongst fruit tree growers. I'm not just talking about the organic growers, but all growers. It works.

One of the worst things about Sevin is the terrible rebound effect it causes. Sevin does such a capable job of killing beneficials that the pests have no trouble whatsoever in gaining leaps and bounds in a population explosion.

    Bookmark   July 12, 2011 at 4:49PM
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I have an effective method for ridding your garden of Japanese beetles that involves no chemicals or those horrid, beetle-attracting traps: Collect beetles in oil in a deli container. Repeat over period of days until beetles disappear.

Long version:
1) Pour about 3-4 inches of super cheap salad oil in a wide mouth deli container. (A Dollar Store pint+ container with a screw top is the best collector.)
2) Slowly approach a plant infested with Japanese beetles.
3) Position the container just beneath the beetles.
4) Position your free hand (or better yet, the lid of the container) horizontally over the beetles, moving swiftly downward.
5) The natural defense of Japanese beetles is to drop straight downward. 98% of them will quickly drop into the oil and will be dead in about 5 seconds.
6) Make a circuit around to the plants in your garden. When I used this method, by the time I got around once, the plants where I had begun often had beetles again. Keep beetle hunting for several days. You will feel obsessive, but all for a good cause.

Five years ago we could peel back our lawn because the JB larvae had destroyed the root system. Through patience and consistency, I was able to get rid of many hundreds of beetles. Mating pairs are worth extra points for the population growth averted. This method is a direct attack on the beetles without endangering the birds or the well water. The beetles were gone completely for about five years and our grass is in good shape. Today I noted a small number of beetles had come to visit, and I started the method once again. It still works like a charm.

    Bookmark   July 13, 2011 at 12:41AM
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I use mskb's method with one small variation. Instead of salad oil, I use tiki-torch lamp oil. After I've collected the day's bounty of beetles, I dump the container's contents at the edge of my gravel driveway and light it on fire. Not as economical as mskb's method, but very very satisfying.

    Bookmark   July 14, 2011 at 6:11PM
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penny1947(z6 WNY)

I found a very good method this year. I collect about a dozen beetles into a container of soapy water place or hang the container close to the plants affected. As the dead beetles in the container start to stink in a day or two it will drive the beetles away. I used a quart sour cream container and poked two holes just below the rim opposit to one another. I ran a piece of string through each hole and tied a knot so that I could hang the container above my bee balm on the fence. Haven't seen a beetle in 2 days. Did the same thing with my butterfly bush only I hung the container on a shepherds hook. No beetles there either and I don't have to make frequent trips to the garden. For container plants that are affected if you move the plants into a more shady location before it gets real hot the beetles won't find the plant.


    Bookmark   July 14, 2011 at 7:39PM
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First Milky Spore is useless in Zones below around Zone 6 and
Merchants should be ashamed of themselves for selling these products north of this Zone. Second as others have said Japanese Beetle traps attract Japanese Beetle. You can use them but keep them at least 300' from areas you want to protect. Never water in the evening as they fly toward the setting sun looking for moist areas to lay eggs. There is so much to say on keeping Japanese Beetle populations under control, from cultural to pesticides that I suggest you find out all you can from your local extension service so you can develop a plan. As they fly well of course, any plan you make will not work if you have close neighbors that do nothing, or encourage these pests.

    Bookmark   July 16, 2011 at 12:29PM
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People that tell you that Milky Spore Disease, "Bacillus popilleae", is not very effective are looking for quick destruction which does not happen with that disease. It takes time to build up and remains effective for a numnber of years and is targets a specific insect, the young grubs of the Scarab beetles while many of the other "grub" control poisons are very broad spectrum and will also kill off earthworms.
Milky Spore Disease is a passive grub control, the targeted grubs must ingest the spores, the spores do not seek out the grubs. That is another reason some feel MSD is not an effective means of control.

    Bookmark   July 17, 2011 at 6:57AM
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Dear Kimmsr.
Never said it was not effective. If I lived where the climate is good for it I would use it myself. I know quite a bit about Milky Spore having known some of the scientists that studied it, and how it takes a while to build up and all that. The winters are just to cold for it to survive much north of where I said. And that is a fact, obtained from something called research. I believe scientists are still working to develop a more cold hardy species but I have heard nothing on the success of this project. Many people who try products will get fooled into thinking they work if they get lucky and happen to use them just before a natural down turn in insect populations.

    Bookmark   July 17, 2011 at 9:47AM
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It is surprising then that the turf grass people at Michigan State University in East Lansing, Michigan say it will work to help control the Japanese Beetle grubs, if properly applied. Very often people will apply this to an infested lawn in the spring, when the grubs are too large for it to work, or some researchers will look at it only in the spring when the grubs are too large for the disease to infect them. If applied in mid summer to catch the grubs hatching from the eggs laid by the adults, and if it is ingested by those grubs, the disease can aid in controlling them.
This disease is only active in the gut of an infected grub and when that grub dies the bacteria again go dormant so soil temperatures have little to no affect on them.

    Bookmark   July 18, 2011 at 7:14AM
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Update from the OP:

The traps have kept the beetles occupied enough that I haven't had to spray anything else. I do see a few about, but most are ending up in the traps. I have five out now and it appears the infestation is slowing a bit as it takes two days to fill any of them. We're still talking thousands of bugs here....the shake them into a bucket idea sounds great for a much, much smaller problem and I do appreciate the information. I'm in zone 5 or 6 depending on which map you use. I have one bag of the milky spore and will probably have to buy a couple more to cover my place reasonably. I'm waiting for the weather to turn and give us some rain since where I need to spread it is pretty far from my water.

I've read at least one thread somewhere that claimed just using the traps could greatly diminish the population over a few years, so I'll probably continue to trap as well as hope the MS works. Other than that, I don't see other controls out there, except for sprays I'd rather not use extensively.


    Bookmark   July 18, 2011 at 9:07PM
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You can find many web sites that claim the traps work, all of them set up by people that are selling those traps. At garden shows over the years where people have booths set up to sell those things I have gotten them to admit the traps are useless but people want to spend their money on something.
The Japanese Beetle has very few natural predators here, although a few from asia appear to be able to live here and parasitize them. There is no one method of control today, it takes a multiple control strategy to maintain some control and that starts with applying grub controls, at the proper time, capturing adult beetles in buckets of soapy water, maybe spraying, carefully with Neem Oil or possibly pyrethrins.

    Bookmark   July 19, 2011 at 7:06AM
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The traps trap beetles. If the argument is that I am trapping more beetles than I would have had without the traps, that may be valid. If I were in a subdivision with multiple attractive beetle targets outside my property I might think differently, but in fact my nearest neighbor is several hundred feet away and I don't think he has fruit trees, though he may have other beetle goodies. If I am clearing my immediate vicinity by using the traps, so be it. When I first noticed the beetles they were already present in very high numbers, sufficient to completely strip a fair sized plum tree. With the traps in place, the beetles are not on a number of plants I would think they would find attractive. Instead I am emptying thousands of beetles from the traps, and the amount is decreasing. BTW, if the smell of dead beetles repels live beetles the trap attractant seems to overpower that effect. The reused bags are now filthy with stinky beetle residue, but the beetles keep coming.


    Bookmark   July 19, 2011 at 3:06PM
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Kimmsr. Please show link to research. I would love to be wrong on this one. This is what I found from Michigan State when I tried, and this article states that they can not recommend Milky Spore at this time.

Here is a link that might be useful: Link I found

    Bookmark   July 20, 2011 at 9:42PM
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Someone must have come in since I completed my Master and Advanced Master Gardening work in 2002 with different ideas. While there was some difference of opinion at that time most all of the turf grass professors at that time stated that MSD was effective in Michigan.
That link has not appeared in any of my searches to date.

    Bookmark   July 21, 2011 at 7:41AM
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That's too bad. Hopes were high in the early days and experiments with Milky Spore. Still if someone is out of the effective zone and want's to try it, I am not going to discourage them, just want them to know what the science is ahead of time. Who knows if enough people try it out of the normal survival range maybe it can mutate and develop some more cold tolerance. Every one thought Nuclear Polyhedrosis Virus was a failure, then almost 100 years after the introduction by the CAES, with no one being able to find it, it popped up and wiped out almost all the Gypsy Moth.

    Bookmark   July 24, 2011 at 9:30PM
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I did Milky Spore back around '97 or so, I'm in CT. Back then we'd literally be handpicking hundreds of beetles a day, usually in the 200-300 a day range. That lasted for probably 3 years. The turf on my lawn also suffered, I had sections of sod that could be lifted off the soil below, like lifting a rug of the floor. Dig and you'd always get grubs.

These days, I kid you not, the number of japanese beetles is statistically insignificant, it's too small to even mention. I see maybe a couple a week. And the lawn has recovered.

So I'll give a thumbs up to Milky Spore here in 6B.

    Bookmark   July 26, 2011 at 2:23PM
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