I spotted this margined leatherwing beetle (Chauliognathus marginatus) on a tickseed sunflower (Bidens aristosa) in a fallow field near home.
The leatherwing beetle, which I thought was a firefly / lightning bug at first, is a beneficial insect in two respects. First, it is a pollinator, something that is critically important. Second, when its larvae hatch, they eat other insects, making it a gardener's friend.
