They may be Cotinis mutabilis, also called figeater beetles, June bugs (different than Phyllophaga June bugs), or green fruit beetles. According to Wikipedia, adults "feed on very ripe, over ripe, or soft fruits, such as figs, or peaches" and larvae eat "decaying organic matter such as compost piles and also burrow into turf and feed on the roots of grass."

Do you have a compost pile or fruit laying around?

Here is a link that might be useful: Wikipedia article on figeater beatle

Sounds like June bugs. We've been having them also. Ext. agent said they were about a month late coming out due to the late cold snap we had. They don't hurt anything, just annoying. Or at least they've not bothered my garden or flowers.