Do you have a lot of grass? Japanese beetles overwinter in lawns, feeding on grass roots.

Perhaps it's time to attack them at the source ... by reducing their food source.

I might suggest doing some research on these creatures so you know the best way to approach the problem. As noted above, these are considered the number one lawn pest in this country in their larval stage. Treating for the larvae - as well as adults - is absolutely necessary to achieve any kind of substantive control. Most sources indicate the Bayer product (active ingredient Imidacloprid) is of minimal effectiveness on adults but works well as a soil drench for the grubs.

Personally, I'd prefer a less broad-spectrum, more organic approach to control but Japanese beetles are not an issue in my area (yet) so not sure how practical that may be with large populations. I'd definitely try milky spore or beneficial nematodes for the grubs and if you are not queasy about it, hand picking as many of the adults as possible.

OSU Japanese beetle control

Japanese beetle control

I'd douse them with rubbing alcohol. From wasps to roaches so far I haven't seen an insect not dying when they are wet covered by it. Then it depends on the size of the bug how long u gotta wait until it doesn't move anymore. Those palmetto bugs sure take a while....

I have minimal Japanese beetles since I've been reducing my lawn every year. Earlier years were pretty large infestations. In my spare time I would take a bucket of soapy water and knock them into it to reduce the adults (when disturbed they often drop straight down so holding a bucket underneath while you poke them works pretty well).

So between hand killing the adults when I could and reducing the lawn, I have very few beetles these days. And I don't use any chemical pesticides.

Say what you want, it can make a difference. By the way, MulchMama, how do you know they come in from five miles away?

I found that beneficial nematodes were a GREAT help. Expensive, but effective.

It isn't the expense of beneficial nematodes that made me quit using them years ago; it was the futility of trying to apply them. Sunlight kills them. They need to be applied to soil that is moist to a depth of 8". They have to be watered into that moist soil, and wow -- calibrating how fast to walk so you get accurate coverage is nearly impossible. But I tried it for five years running, and picture this:

Middle aged woman outside, at night, in the rain, watering the lawn with nematodes, and not having a clue if I was getting the coverage right because it was dark. Every year, my husband stood on the porch during stormy nights, laughing at me. He used to tease me and say that little sponge that "claimed" to contain the nematodes was just a plain little sponge.

Those Japanese Beetle traps they sell at the big box store are great...at attracting the little buggers.

One strategy might be to get some of the traps and place them down the block from you...to lead them away from your property.

FWIW,
I buy concentrate Sevin (carbaryl) and mix my own solution for spraying with a pump sprayer. We also spot spray as needed. So far this has been effective at greatly reducing their numbers. It also takes direct contact so that the insecticide is absorbed through their exoskeletons, which takes a bit of time. Also, you have to understand, there will be more that come to replace them in a day or two. So while you may kill 90%, "everyday the paperboy brings more" (think Pink Floyd). So you will not be totally rid of them until they die on their own. They seem harder to kill early than later as well.

Arktrees

Thank you everyone for your replies. I appreciate them so much.

I didn't realize that Sevin came in a concentrated liquid form. I will definitely check it out. I've also never heard of nematodes. So I'm going to look up to see what that exactly is.

Here's an update on the situation:

I just came in from mowing the lawn, and as I drove by I could see that there are no Japanese Beetles to speak of in my yard; or at least not on any of my plantings. Having said that, my shrubs look like they were involved in a nuclear fallout or perhaps like a volcano erupted nearby. They are are completely covered in the white powder!

As for treating the yard for slugs, I know we have TONS of them. When we planted the shrubs this year they were everywhere in the holes we were digging. I wonder though if it would be a futile attempt because I live way out in the country, and I am surrounded, in all directions, by hundreds and hundred of acres of prairie. To illustrate, we have bunnies that live in our yard, and just a moment ago the most adorable groundhog was hanging out by our back porch.

This may be a dumb question (if it is, please forgive my ignorance) but do the beetles also attack in cities and in the suburbs or is this more of a rural issue?

I am interested in the traps. I forgot about them. I know some people say they attract the beetles so much that it can, in the long run, make the problem worse, but I think I'm already in the midst of "much worse".

It's just amazing to me that 3 years ago I never saw one, then last year I saw a good amount, and this year they have evidently taken over my yard. :Thanks again, everyone for your replies. It's nice to find people who know so much about so many things that I care about.

Birds are part of the answer. Birds eat beetles, slugs, caterpillars. Perhaps part of what has happened is an imbalance in the web of life around you. Normally these things keep each other in check. Adult birds raise chicks on insects - thousands of them in just the two weeks that the chicks are in the nest. Most adult birds also eat insects themselves, especially birds classified as insectivores - not cardinals but warblers and many other birds that you don't often "see" but they are there.

ilt,
Sounds like you are in the initial wave of the invaders. When we moved in to this house, that was where it was located. They had gotten here a year or two before and multiplied like crazy. Insane number of the %@#$^#$ things. In any event, their numbers have decreased each year since. I'm sure the local wildlife is learning to make good use of them, and probable some biocontrol is following them as well. While I can't say the same will happen there, or even that it will continue here. It is common for a new invasive such as this to be at it worst in the first few years, and then numbers subside some amount.

Arktrees

Arktree

I'm going to use netting next year for the 6 weeks that the beetles come out and eat. That way my yard won't be exposed to pesticide residue, and I can basically set it and forget it.

The best way to use Japanese beetle traps is to give them to your neighbors for Christmas presents.

Imidacloprid systemic drench - if it's applied early enough, as in before beetles are evident - can help a great deal. You'll still see beetles, but the leaf damage will be greatly reduced.

A recent discussion in the Vegetable Forum had some ideas that may help you in an isolated country setting. Most of the grubs grow in turf areas that can be treated with milky spore, a bacteria that kills the young grubs. It grows in the soil from year to year and can reduce populations more in later years. Traps placed far away from your prized specimens can lure in thousands of adults for a death before egg laying. Just don't dispose of them where eggs may hatch and get out of the dead bodies. Spot treat nearby areas with heavy infestations with sprays. You may be able to have good control in a year or two. The fourth post on the linked discussion tells of one rural landowners success against JBs.

Yes, cities and suburbs definitely have JBs. And there is no way I can treat all the individually owned nearby areas to get good control. I have often seen grapevine, virginia creeper, hollyhocks, etc covered with so many JBs that the leaves were hardly visible.

Here is a link that might be useful: JB discussion

The big unknown: "hundreds and hundreds of acres of prairie".

Does that function like turf for JB grubs (larvae)? Or is it minimally useful to them?.......I don't know.