5.5 mm. Found in car while parked for a pit stop at the Wawa convenience store after a trip around the landfill (grassland, adjacent salt marsh, and of course garbage). No longer unIDed; many thanks to Charlie@LincsBeetles for the genus ID. O. melanopus looks like the only only on BugGuide that's in range & matches in appearance. It feeds on grasses, so landfill habitat makes sense. Nonnative, a pest of crops.