This species is really doing damage in my garden this year as it did last. The beetles are like small "june beetles' and feed at night on plant leaves. Go out tonight with a flashlight and examine any plants on which you've had lots of bugholes with no obvious bugs in the daytime.
They especially like my Centaurea montanta, most types of Chrysanthemums, peaches, and a few are found on many other garden plants. A few were there last night finishing off my sad nearly skeletonized Geranium pratense ( a hardy geranium) They were active on a my ailing Peach and hardly on my healthy looking Peach so they may prefer, or be more able to feed on, sick plants.
Handpicking is an option but I'm getting discouraged after 150 bugs in two nights.
Imidacloprid (Merit) insecticide is toxic to bees, according to recent studies. You may want to think about that before dosing actively flowering plants with this chemical.