Forgot to close the forge flue one night and woke up to find a whole swarm of moths had decided my coal pile was the perfect place to lay eggs (gross). Spent the next two hours with a shop vac instead of a hammer. Anyone else had a critter take over their workspace?
Moths are actually drawn to light, not coal. Their larvae might eat fabric, but the adults don't lay eggs on fuel. You probably had some other insect, maybe beetles or flies, that were after the organic material in old coal. It's a common mix-up. Still a nasty surprise to deal with first thing in the morning.