It was the Four O Clocks. The JP's flock to them, but it's poisonous to them. They eat it 'cause they love it and drop dead right then and there. The white geraniums are just supposed to repel them. Four O Clocks are more effective.

Mirabilis (Four O'Clocks) is very effective and does seem to be poisonous to the beetles. Actually, once these plants are grown and blooming, I have found them to be a deterrant in that the beetles seem to avoid wherever they are planted. Meanwhile, spray your rose with a solution: 1 tablespoon ground cayenne, 1 tablespoon garlic juice, 2 teaspoons baking soda, 1/4 teaspoon mild dish detergent or Safer's Soap, all mixed into 2 quarts water. You will have to re-spray after every rain, but the mix does seem to get rid of both beetles and aphids. The japanese beetle larva has probably infested the lawns and grass areas in your neighborhood; get together with your neighbors and all apply "milky spore" which seems to be the only thing that will get rid of the larva. Very expensive but the more spore you buy at once, the cheaper it is, plus you really don't want their beetles eating your roses next year.