Yellow Dung Fly

The flies were about 8-9mm long. They were brown with sparse black hairs on the thorax, and had red eyes and antennae. I spotted them mating on scat (probably from Red Fox, Vulpes vulpes) that was on a rock in a deciduous forest. There were many small bones and feathers in the scat. My kids and I often rest on this particularly comfortable and large rock when we hike these woods, and over the past few months, foxes have been using it as a latrine. My guess is they are trying to claim the rock as their own, and so far they are winning the battle.