I have found that 100+ degree temps get rid of both thrips and JBs. But alas, no roses want to grow either.

Buford, we have triple digits temp in MD for 10+ days and JBs are in full force here. I can collect gallons of JBs every day. Not sure temperature helps.
Olga

We had high heat in 100's for a few days which didn't bother Japanese beetles at all. I have to harvest ALL my fragrant roses in bud-form before the bugs eat them. I find out that if I cut roses in bud form, 1/4 opened, then the blooms release more scent in the air-conditioned indoor temp.

If I let the blooms fully opened in the hot sun, they lose all that precious perfume, and the scent only attract more bugs. I suspect the JB eat flowers for moisture. The thicker and more succulent the petals, the more they attract JB.

The problem is when you have JBs in heavy numbers, you will not have " rosesin bud form, 1/4 opened". Buds will be eaten when they are pea size, many days before any petals could develope.
Olga

Petroleum jelly is worth a try...I KNOW the STP works (oh by the way, I have used Dollar Store STP type product and it worked well too), have used that method for over a year now. And to add, the solo cups are great conversation starters! :) Folks always want to know what are those cups for...

Has anyone tried this?
"New biocontrol for Japanese beetles: Gardeners can take some home to release in garden" See bottom link.

Also recent research paper:
http://www.bioone.org/doi/abs/10.1603/EN10241

Here is a link that might be useful: New biocontrol

"004 Root Application of Potassium Silicate Reduce Feeding Damage to Sargent Crabapple Leaf Tissues by Adult Japanese Beetles" (see link below)
There also is a 2001 report by A. M. Shirzai and F. D. Miller in the following:

Shirazi A.M. and F.D. Miller 2001. Root application of potassium silicate reduce feeding damage to Sargent crabapple leaf tissues by adult Japanese beetles. p. 390. Poster Abstracts. In L.E. Datnoff et al., (eds.) Studies in Plant Science: Silicon in Agriculture Vol. 8, Elsevier Science. B.V., Amsterdam.

Here is a link that might be useful: link for first article above

Thank you, Henry, for those link. Too bad I need a permit to buy the infected JB from Michigan State, in oder to infect the JB in my garden. It's nice to learn from the link that JB eggs die in dry clay, so next year should be better (thanks to the current drought here).

Someone suggested birds as predators for JB. That might be the case. When I first moved into this heavy clay place, there were no trees, but tons of Japanese Beetles. At that time I used a big plastic bag, disturb the JB so they fall down into the bag, then crush them. It was messy, I should had used a big paper brown bag.

Twelve years ago I planted 26 trees, put in 3 bird baths, and my neighbor feeds the birds. Now the birds far outnumber the JB. Yesterday I went JB-hunting, and could only kill 6 - the birds took care for the rest.

Strawberry- thanks for the stp hint! I bought non toxic blue sticky traps and they do work! So i bet the stp works cheaper!
My daylillies harbor Huge colonies of thrips and yesterday i noticed my orange one just full of thrips i can not eradicate ! grrrrr. (roses look like heck this year).
Stuck a sticky trap out last night and this AM theres only about 10 thrips on the lillies and about 100 thrips on the cards. Squeee! When i saw that i practically skipped into the house singing zipadeedoo dah! (what a wonderful day!).

Ive tried planting 4 oclocks (wintersowed about 500 seeds) and used about 12 potted geraniums a few years ago .

the only thing they did , was give me enjoyment of flowers, however, I dont like the pelargoniums that much, they remind me of funeral homes for some reason(dont ask me why I dont like marigolds, but I do not care much for them either) , so I gave the ones I had away, I had some reseeing 4 oclocks for awhile, but they eventually died out..

they had no impact on my jbs that I could determine.

I might buy some of the cedar oil next year and spray it around, we will see.

I dont think using stp is all that organic either, what are you going to do with the product afterwards? is that any better then spraying? Im not sure it is.

Unfortently, with people with high #s of jbs, Ive yet to see a actual organic means of controlling them in any #s. I will continue to try, as I hate to spray, mostly due to having young children.

Silverkelt

I think I meant the combination of high heat, drought and hard clay. I have read that it prevents the JB grubs from emerging. Whatever it was, we haven't had JBs since we had those awful drought years. So I guess it was good for something.

I may try the STP as well. I didn't know that thrips were in daylillies. I probably have tons in there. But they don't seem to ruin the flowers like they do roses.

My understanding was that some kind of wasp (I forget which one) is the JB killer. Supposedly that is the natural control that places like Kansas and other farm states have introduced to keep the JB somewhat at bay.

Some places in Kansas claim they get some JBs. I saw a small handful in my garden--but they were all dead by the time I saw them. Not sure exactly how they died (while lying on the rose bloom), but I always say friendly words to any wasp that may fly past me--just in case!

That was the 1.5 day JB attack in my garden.

Kate

I went no-spray many years ago. Encouraging birds, lizards, toads & frogs helped a lot. The rose area has a couple of bird feeders, three waters, including one big plant platter on the ground that the frogs love to soak in. Has some large rocks in it so tiny birds feel safe using it for baths & drinking. Please, NO OFFENSE intended, but I didn't have outdoor cats or dogs, which helps if you're trying to establish a wildlife-friendly yard. Yes, I LOVE pets!!! If you have outdoor pets, maybe you can place feeders & water in more raised or sheltered locations.

Hang a few bird houses in sheltered places & I'm careful not to disturb bird nests in nearby shrubs & trees. My dad's fruit trees (also native species) attract birds, too.
They sample a bit, but do little harm.

A few overturned broken pots under shrubs make good toad hideouts.

I have sprayed the veggies & some herbs that were getting gobbled. Used a solution of blender-shredded artemisia leaves--bitterest stuff I could think of--& it seemed to work. So now I clip stems & leaves to mulch them around the affected plants. Good luck.

Not sure how they work, no JB's here but I read this article today

http://www.gardensalive.com/article.asp?ai=482

Here is a link that might be useful: Gardensalive Link

I think the best organic way is to leave it alone and let nature take care of it! BUT easy for me to say..I don't have those nasty JB's. They are gross.