A little over an inch long. Eyes too narrow for Canthon vigilans. Lacking vivid color of Canthon viridis. Confirmed by v. belov/BugGuide:
@ceiseman I’m not 100% sure this is even a leaf mine, but it looks like one to me. I could not collect the plant for closer examination or rearing because it’s a state listed endangered species.
Gumballs scattered on the ground within an open ridge line.