Its head was constantly bobbing and swinging around, but eventually I managed to get a shot of its face, such as it was.
I put it in a jar of soil with some leaf litter, and it overwintered in the fridge with all the jars and vials of leafminers. Two days ago, it emerged as an adult.
I had figured out shortly after photographing the larva that it was some kind of soldier fly (Stratiomyidae), and when I showed photos of the larva to Norm Woodley he was fairly certain that it belonged to the genus Allognosta, subfamily Beridinae. So now that I had an adult fly, I ran the photos through the key in Maurice T. James’ 1939 review of the Nearctic Beridinae, and I easily arrived at Allognosta fuscitarsis. With Norm’s blessing on this ID, I sent the fly back out into the yard yesterday.
His face as an adult is decidedly more pleasing to the eye.