Well... I may have found the culprit. I just went out with my flashlight and went exactly to the scene of the crime, and right there I found a sizable millipede. Yes, I know, those things that hide among the leaf litter and eat dead and decaying organic matter. However, this fellow was sitting up on top of my gravel and not hiding in the soil or leaf litter. It was shamelessly out in the open, right next to live leaves. Needless to say he is no longer with us so I will keep my eyes peeled going forward. And tonight... I shall sleep.
