I don't know the first thing about the chinese rose beetle. Of the states, isn't it found only in Hawaii? You might contact Baldo Villegas (see link) for advice.

I do know that neem oil is a moderately effective antifeedant for japanese beetles and perhaps it works for the chinese rose beetle but you have to buy the right stuff which is the original neem oil and which contains the actual repellent, azadirachtin. Much of the neem oil on the market is "clarified hydrophobic extract" of neem and this is basically just another plant oil, analogous to vegetable cooking oils.

Here is a link that might be useful: Baldo Villegas

Mike-thanks for the tip about the neem oil-I'll check my bottle in the morning to see if I used the 'good stuff'. Someone suggested that it might be more effective if I mix in some rubbing alcohol but I'm hesitant-have you heard of this?

Yes, I do think the chinese beetles are regional but you never know who's out there, right? I heard that the beetles are attracted to leaves that have already been chewed because they release ethylene gas so my next idea is to try to figure out a bait that releases same.

Now I have a question about the Merit-just in case-but I'm a little nervous about asking because I've noticed that things have been a little heated up around here lately. If you apply it as a drench around the base of the plant what is the collateral damage?

Mauirose, the good neem is an ethyl alcohol extract and it's diluted with water just before it's sprayed. The active ingredient, azadirachtin, is stable in water for only a few weeks - that's why the alcohol solution rather than a water dispersion is sold. Rubbing alcohol is usually sold as a 30% water solution of isopropyl alcohol. I can't see what good it would do and if you add it to your concentrate, the water will destroy the azadirachtin.

Just a direct answer to your question about Merit, with no judgements: Comparing a soil drench of Merit vs spraying, the soil drench is safer for you to apply, puts much more insecticide into your garden, takes longer to move up in the plant and become effective, probably lasts for up to 6 weeks, and is likely to render the entire plant toxic to any insect that eats the leaves or flowers or harvests the pollen.

Also, Merit is known to encourage outbreaks of spider mites.

If you can't find whole neem oil-- and I've never seen it on a garden counter-- you may be able to find azadirachtin extract of neem. Green Light I believe packages one such. Azadirachtin is listed as the active ingredient.

Also in the study Mike_Rivers mentioned, cyfluthrin was a very effective japanese beetle killer and repellent. Bayer packages a cyfluthrin-only spray concentrate. It is less likely to cause mite problems because it is also a miticide. If you decide to go that route, please don't apply it to open flowers, because, like almost all insecticides, it is harmful to pollinators. I'm sure the county agent would say the same thing about Sevin.

Thank-you so much gentlemen!

It's great to be able to bounce a few ideas around with a knowledgeable group of people. I am so appreciative and amazed at the generous way information is shared whenever I search this forum.

"Clarified hydrophobic extract"-exactly what I have. I'm scouting around for something else-any brand name suggestions? And I'll just say no to adding the alcohol-goes to show can't trust everything you hear. I really want the neem to work-don't like to spray anything but if I have to seems like it might as well be Neem-fungicide, miticide, 'antifeedant', and organic to boot-good bang for the buck!

Thanks for pointing out that Merit, as a systemic, would of course be in the pollen of the flower-I hadn't thought that through. I don't even kill centipedes but I wasn't feeling too badly about killing anything chewing holes in my roses! Bees-another story-already under so much pressure from the mites.

I will be researching the cyfluthrin-thanks for offering another alternative.

Another idea that I have been toying with is using Neem Cake fertilizer. I have a bag in my shed right now that says 'minimum 7% Neem oil'. Wonder if this would enter the plant systemically if applied as a top dressing or tea? Also says 'harmless to earthworms, beneficial soil organisms, animals and people' :)

Mauirose, Safer's Bioneem is one example of authetic neem oil. It contains 0.09% azadirachtin. I think if you search the web, you might find neem oils with a higher concentration of azadirachtin at a similar cost - see link for one example containing 1500ppm azadirachtin (0.15%).

Here is a link that might be useful: Herbal Remedies

Not to hijack the thread, but I finally went and got my little half pint of Neem which I've had for years, acquired when I was actively growing orchids. It was "new" (to the western orchid community) at the time I bought it.

It's on the Dyna-Gro label and the label just says "100% Neem Oil."

Is this likely to be accurate, or were labeling requirements back then less stringent and it's something more mundane? Am I sitting on a gold mine? Should I take bids??? LOL.

DynaGro is cold-pressed neem oil, a third type of product. Cold-pressed neem oil usually contains azadirachtin at about 0.15% or slightly higher concentration but neither the label nor the MSDS for DynaGro Neem mentions the concentration of azadirachtin. I guess it's assumed that the words "cold-pressed neem oil" are self-explanatory.