In hopes that the Japanese bettles are not reading this posting, I have noticed their eerie absence on my roses so far this year, in contrast to their presence on roses elsewhere but nearby (a cemetery in Lancaster and the rose garden at Longwood Gardens). Could it be that the ornamental onion Allium Millenium and mountain garlic Allium Summer Beauty I planted to deter bad bugs and attract good ones are actually doing what I hope they are doing?

I planted these Allium cultivars near my roses starting mid-summer of 2017 because the rose gardens at the New York Botanical Garden, Brooklyn Botanical Garden, and Scott Arboretum were doing so. Both are rhizomatous Allium, rather than bulbous Allium, and bloom all summer rather than going dormant like the bulbous ones.

Does anyone else have experience with this strategy for detering bad bugs and attracting good ones?

Ornamental Onion (Allium 'Millenium')
Mountain Garlic (Allium lusitanicum 'Summer Beauty')

While I can't address your question. I can say that I sure hope so. Every year when they arrive the same thought crosses my mind. Wouldn't it be something if a simple plant or harmless spray could keep them away.

As far as I know, the allium family mostly deters less aggressive bugs like cucumber beetles. When the Japanese beetles get bad, I think nothing short of a blow torch would deter them. Kill them - yes, gloved fingers do wonders for that. Deterrence comes from putting the milky spore down on your lawn and looking forward to better years to come. It's a long-term solution.
Do let us know if it seems to make a difference though. Allium are pretty so it can't hurt, well as long as you don't get one of the invasive species of allium. I like the idea of all summer bloom rather than just late May from Allium.
Cynthia

nippstress said:As far as I know, the allium family mostly deters less aggressive bugs like cucumber beetles. When the Japanese beetles get bad, I think nothing short of a blow torch would deter them. Kill them - yes, gloved fingers do wonders for that. Deterrence comes from putting the milky spore down on your lawn and looking forward to better years to come. It's a long-term solution.
Do let us know if it seems to make a difference though. Allium are pretty so it can't hurt, well as long as you don't get one of the invasive species of allium. I like the idea of all summer bloom rather than just late May from Allium.
Cynthia

About 10 years ago I put milky spore one of the gardens where roses grow, but not in the "lawn," which would have cost too much for me. (That may have been a waste of money as JBs probably develop in lawns but not in gardens.) Also, I have enjoed flicking every Japanese beetle I see into a jar of soapy water. So perhaps I am somewhat ahead of the JB war for one or both of those reasons, not just the Alliums.

Or perhaps the JBs are just gathering their forces for a major attack in July.