We haven't yet concretely identified these beetles, which we suspect belong to the genus/species linked below (they have no common name). If so, they appear to be locally native, and we routinely receive a few questions about them feeding in the buds/blossoms of Black-eyed Susans (Rudbeckia) and Coneflower (Echinacea).

• Maryland Biodiversity Project -- Brachypnoea tristis
• BugGuide -- genus Brachypoea

No intervention is necessary. You can clip off damaged buds if they appear to chewed to open properly, but otherwise there is no preventative method of control, and the life history of this particular beetle (such as where their grubs feed) may not be understood yet, since there is little information about them in gardening pest reference material. Using a barrier to exclude the beetles, like netting, would of course block pollinator access as well, and using a pesticide is naturally not recommended when dealing with a minor pest on plants that will attract pollinators and other wildlife. If too numerous, you can try knocking them into a pan of soapy water to drown, just like with Japanese Beetles and some other nuisance beetles. Many beetles tend to either take flight when disturbed or drop to the ground, so would be fairly easy to knock off a plant.

Miri