Yes, I tried garlic, garlic chives, and geraniums. They don't repel at all. Funniest part was finding JBs ON the darned garlic chives!!!

Like Karl said.....if you're growing anything, you'll have them. The only way to get rid of them is to rip out everything alive & green and go with a concrete lawn. They only are present for one flush, and my buds still opened with no problems, even with JBs feeding on them. They only annoy me because they are big, clumsy, and get stuck in my hair while I'm out gardening. Really quite gross. The heat was a larger problem this year than the bugs.

If it's any consolation, I did notice that my minis were relatively ignored. I'm guessing it's due to the fact that a lot of minis have no fragrance. Another funny thing---you can spray yourself with Off! and the silly things will still land on you. Pick & squish if you have less than 20 roses. More than that & you'll have to quit your day job to keep up with them.
---Laura

I tried Rue and all that happened was I got a rash from brushing up against it. Didn't bother the beetles though.

This spring at the garden expo in Madison I talked with an entomologist from the UW. He said that there is very little you can do about the beetles. If you keep killing them every summer it does work to reduce their population. The milky spore doesn't work so well up here though since it is too cold for the bacteria. I went ahead and did it anyway since I had to do something. He said that after an area has been infested for about 10 years that the beetle population will start to decline. They're not sure why that happens but think it might be that they get infected with a bacteria when their population gets high enough. So his main advice was just to wait it out.

I tried milky spore,it did not work, but maybe I applied at the wrong time of year or something. I may try grub-ex. I did notice this year they were less, but I think that was because I planted roses that had NO scent (kordes) they seemed SLIGHTLY less attractive.

The one the jbs never bother is Valentine because it is dark red, has no scent and since mine are own root they never get over 1-1/2 feet tall.

I have heard marigolds are a reppellent, but then I also heard that some plants serve as "trap" plants and they go to those rather than the roses.

I have found they prefer roses best of all the plants

An article appeared in the garden section of the Peoria Journal Star today and said JBs die when temps exceed 90F. It said as the summer's extended 90F days pile up, the JBs decline.

This year we did have a very hot August and the beetles seemed to be less in August than last year, but I seem to remember that August 2009 was just as hot as 2010 and the JBs were an epidemic and stayed around until October.

Anyone care to comment on the temperature theory?

I think that the theory holds water for only one reason---that in Illinois, the GARDENERS decline when it gets above 90 and everyone goes into the air conditioning and stops noticing the JB menace.

I know that the newspaper, master gardeners, and U of I extension all say that the season only lasts 2 weeks, but they must have a 3-week "margin of error" in their estimate. For the 8 years I've been gardening, they always seem to hang around for at least 6 weeks. They get the better part of 2 flushes of all my roses. They are also MOST active when it's hot, sunny, and bright outside.

And I wasn't kidding about ripping out the grass. The grubs stay in the soil under turf over winter. No turf, no beetles next year. But I suppose it would be a little tough to get the entire neighborhood on board with that plan.....

I found rose chafer beetles, which are a plague in May-June in CA far more unsightly than JBs. My experience confirms what was said above, no lawn, no beetles.

Me, I think lawns are an anachronism, unless you play lawn tennis or croquet. They do make a nice backdrop for a row of brightly colored HTs or floribundas, but, IMHO, require far too much time, water and money.

I almost have my DH convinced to take out a big chunk in the backyard and replace it with astro-turf, so that we can have a putting green for practice.

Seriously, though, Terry---did you notice fewer JB's in the heat? I know they're more active, but I can't say if there were more or less of them. Seemed about the same to me.

This year there were less in number and were out of here in August...but when I say 'less' there were still hundreds.

Last year there were so many it was seriously like a plague at my place...they were on the daylilies, wisteria, varegiated Japanese hedge, you name it....they ate it. It was awful; I couldn't walk outside without being bombed. I had them until Halloween. And I know they love the HEAT; that's when they're most active; they disappear on cloudy, rainy days.

And Laura, your idea of tearing up the grass sounds good, but you do know those suckers can fly in for miles, don't you? So if your neighbors have them, and since you're in the midst of farmland central, well....

Hehe, yeah. That's why I still have my grass. We have a concrete basketball half-court in the backyard; that's where I'd really like the putting green to go. Concrete is so---yuk. Also, I think rainy and cloudy days lull the JBs to sleep. Either that, or they're like the Wicked Witch and can't stand to get wet!

I read somewhere on a Edu. site not to smash JB's as the scent draws more JB's to the area.
Anyone else hear of this?

Yes, I had heard that, but can't lend any credence to it. I smash. It feels good to smash them. :)

The one thing that certainly draws more of them to the area are the traps with the hormone. I don't believe that smashing releases the hormone; it's more likely that they're yelling HELP in JB dialect.

Oh, I have noticed one thing. When I smash, if I don't dispose of the carcases, other JBs will visit the recently departed. They seem to be attracted to the dead bug, but not necessarily the smashing.

This entire thread is really good info and I'm glad to see that my fellow rosarians are sticking to common sense and science instead of folk lore....companion planting for beetle prevention indeed!

And flaurabunda, the squashed beetles may be attractive because of released sex pheremones...a little necrobeetlephilia perhaps?

Here is a link that might be useful: Garden Musings

Ewwwww......now I'm going to be obsessive/compulsive about hand washing!

If you all think JBs are bad, you should see the Green June Beetle, which arrives the same time. They are similar in grace & intelligence (none whatsoever), but about 3 times the size of a JB. They don't do any damage, but they are loud & love to do kamikaze raids at your head.

Here is a link that might be useful: Green June Beetle

Yeah you get hit by a flying june bug it feels like someone hit you with a rock! It hurts.

Even worse to get hit by a June bug when you're on a motorcycle...I speak from experience.

"Forty-one plant essential oils were tested under field conditions for the ability to reduce the attraction of adult Japanese beetles, Popillia japonica Newman (Coleoptera: Scarabaeidae), to attractant-baited or nonbaited traps."

See link below.

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