These have suddenly appeared in large numbers during the last week, primarily on white sweet clover (Melilotus alba), but occasionally on alfalfa plants as well. There are patches of sweet clover where nothing is left but a stalk with a bunch of shiny green bugs clustered at the top like a bunch of grapes. I don't recall anything making much of a dent in sweet clover around here in the past, though it's possible these beetles could have been around in smaller numbers and I wouldn't have noticed them.The first picture shows several on a sweet clover plant - the closest thing I've found to them looks-wise in the guide is flea beetles, but these are around 8mm - too large for a flea beetle?