I don't know about that, but if you look at the other thread on Japanese Beetles, you will see comments of Prof. Daniel Potter of the University of Kentucky (relayed by me) that Peonies have a strong attraction for the spring Tiphia wasp (Tiphia vernalis) which parasitizes Japanese beetle larvae. (Yes, Peonies and only Peonies; many other flowers were tested but none were as effective at attracting the Tiphia wasp.)

Keep in mind that about 50 percent of what Baker has is pure malarky while the rest is questionable at best.