Helophilus fasciatus larva, a rat-tailed maggot, about 2 days old. Eggs were about 3 days old when they hatched. I tried my darnedest but found it very difficult to capture a decent photo of this tiny, writhing maggot. These larvae are transparent so you can see their insides under magnification. Here the back half of the animal is clear enough to see that the retractable breathing tube ("tail") is actually 2 small white tubes, running side by side. I think most of the looped tubing you see in the maggot's main body cavity is an extension of the breathing tube that's held inside the larva until needed. I'm not sure what the larger, wavy tubes closer to the front are.