I had seen the burrows near adults the previous evening and presumed all the larvae had transformed already. However walking by the next morning I noted that three burrows were still occupied. One larva was cooperative and not too shy as I set up a camera over it. Getting light down into the burrow was a challenge--by experimenting, I finally got a decent flash fill.
Virginia Metallic Tiger Beetle - Tetracha virginica (larva, diameter of burrow ~7 mm)
bugguide.net/node/view/3024
Edit-1. One more photo of a member of the same group added here--it was taken two days later. I feel it is valid to just file it under the same observation--there are three or four burrows all together within just a few cm of each other.
Edit-2. Added one photo of a tight grouping of four larvae from the same site. It includes the two larvae I have posted previously.
Edit-3 (29 July 2020). Added photos of a 3rd instar larva I was able to pull from its burrow alive. This is one of the ones I photographed in its burrow initially--they are pretty sedentary at that stage, I believe! Length of this larva was 28 mm, base of mandibles, to tip of abdomen. Quite the hefty critter!