I remember that I did find them on the surface. I think it was just outside the edge of a piece of plywood or something, and I do believe it was in the evening (both based on my comment that I was was going to go back and look for it the following day). The area wasn't sandy. I'm not sure exactly how to describe the the topsoil other than it became extremely dusty in the summer. Given the date I posted this, it definitely would have been a moist climate underneath a piece of lumber sitting on the ground.

I did go back the next day and found this same glow worm. I kept it in a jar for a month or so and fed it millipedes every day. It had a voracious appetite. Late at night, when my eyes were adjusted to the dark, I could see the bioluminescent glow, although it was very faint.

I eventually released it, in a similar habitat to where I found it, when I was no longer able to find enough millipedes to keep feeding it every day.

I've never seen a glowworm before. I will see if I can find it where I left it tomorrow. I'd love to get a photo of it glowing! Thanks!