Japanese beetles are invasive creeps that spend part of their life feeding on roots, then emerge to feed on the flowers and foliage of ornamental plants.  These creeps are emerging now, and are looking for a meal.  They are indiscriminate pests, but their favorites include rose flowers and pruple leaf plumb trees.

To learn more, check out this site: http://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note44/note44.html