In part, it says, "To increase the number of Tiphia vernalis near you,
and thus increase their toll on the JB grub population, Prof. Potter
suggests that you should PLANT PEONIES. ... The attraction of Tiphia
vernalis to peonies is very specific: "We screened dozens of other kinds
of spring-blooming flowers and most of them did not attract appreciable
numbers of Tiphia." The Tiphia are attracted to "honeydew" produced by
aphids and scale insects (that live on foliage of many types of plants),
but not to flowers other than peonies."
It also says that the effect on Japanese Beetle numbers is likely to be
minor, but it says that about all the control methods discussed. I know
nothing about any of this myself, you understand. I just stumbled across
the discussion.
Bill
--
Men never do evil so completely and cheerfully as when they do it from a
religious conviction. - Blaise Pascal