You'll need to check to make sure they're OK to grow in your area. The source of this list is Shiner, Townsend, and Potter of the University of Kentucky.
Acer negundo, rubrum, saccharinum (boxelder, red maple
silver maple
Buxus sempervirens (boxwood)
Carya ovata (Shagbark hickory)
Cornus florida (flowering dogwood). Note, you may want to
go with Cornus kousa for dogwood anthracnose
resistance.
Diospyros viginiana (Persimmon)
Euonymus (though it's often attacked by Euonymus scale)
Fraxinus americana, pennsylvanica (white and green ash)
Ilex (holly, all species)
Liriodendron tulipifera (tuliptree)
Liquidambar styraciflua (sweet gum)
Magnolia (be careful and select cold tolerant species)
Morus rubra (red mulberry)
Populus alba (white poplar)
Pyrus communis (common pear)
Quercus alba, coccinea, rubra, velutina (white, scarlet,
red, black oak)
Sambucus canadensis (American elder)
Syringa vulgaris

Boxelder, black oak, and American elder may suffer some light feeding.

If you'd like a copy of a talk I've given on controlling Japanese beetles (plus the speaker notes) (6 slides/ page), drop me an email and I'll snail mail it to you. The talk is geared toward a Maine audience, but, the exception of Japanese beetle emergence times, the methods are fairly universal.

If they don't like magnolia then why are my Little Gem Magnolia's blooms being devoured as we speak. I find about 6-10 beetles on each flower. I might have to go by some Sevin.

I'm piggybacking on this forum because of the name "Japanese Beetles", rather than open another of the same name.
I have a Siberian Elm that the beetles just love. It overhangs my driveway, so that the driveway si covered with leaves, dead beetles and when I sweep up, a lot of 'beetle guano(to use a nicer term)'. Has anyone seen an analysis of this? Everytime I sweep up the leaves and dead beetles, there is about a cup of this guano. Probably make a decent fertilizer for some potted plants.
Roy

I've not seen any on my saucer or star magnoilas.

They also have not been found on my lilacs, dogwood, hydrangea, forsynthia, peony or any lillies that I have tried. Thought, my shrubs are in plenty of shade, which the bugs don't care for.

We have a plum tree in the sun. They devour it. I think I'll get rid of and plant a couple of pear trees.

I too have problems with them. I live in wisconsin, and they completely defoliated my cherry, grapes, roses. I have tried the traps, which work okay, but I hear bees are a natural enemy to them, so I might try ro get more around here. I even treat my lawn for their grubs, because they infest it every year, and that brings in the moles. Does anyone else know of any animal, bird, or other insect that are enemies of japanesee beetles? I have tried the spray on them , but they just fall off and then fly back on. I wish they would just go extinct.