Thanks for the comments, everyone, definitely appreciated. Strangely, the maggots were apparently just in some leaf litter, without any obvious dead animal. I was surprised by this, and that is why decided to take the shot. There were some predatory beetles there eating them, but I could not photograph them - they hide very quickly when the leaves were disturbed. John - you are right about sensor dust, I didn't clean it in about 2 years and change lenses relatively frequently. Fizzog and Brian - this gall was much bigger (about 10 mm) than what I usually see. Probably most galls I see typically are caused by mites or aphids, and this big one is probably caused by an insect larva.
