Sept 14 2019
Spotted a new sea monster lurking in a S. Yellow Jacket pitcher. It's huge (relative to the blobs/ mites), around the size of the midge larva. It looks like it has a large air bubble inside it. Definitely not a midge. I think it's the larva of flesh fly.
According to Robert Zottoli at boginvertebrates it looks like the Fly Larva Blaesoxipha
Larvae of this species live exclusively in the fluid filled cup of the pitcher plant Sarracenia purpurea. I have never found more than one specimen in a single cup. They float near the liquid surface feeding on insects (mainly ants) that fall into the pitcher plant before the ants sink to the bottom. In one study, it was determined that Blaesoxipha consumed up to 50% of the insects that fell into pitcher plants. The larval head is incomplete. Note the black mandibles in the photograph and videos. They move parallel to one another as the animal feeds. Blaesoxipha floats, head down, with the deep, posterior, spiracular cavity extending slightly above the surface of the liquid. Two orange, raised ,spiracles lie within this cavity. Air is moved through the spiracles into two large tracheal tubes. The large white tubes, branch into smaller tubes (Visible) that deliver air, containing needed oxygen, to larval tissues. Larvae eventually crawl out of the pitcher plants and pupate on the bog surface.
I’m not sure if this is the exact species, but it seems related. The black mandibles look right, but the air cavity (spiracle) seems to be in the wrong place. It's in the middle, instead of the posterior of the animal.
This larva was only there for a few days. Presumably, it pupated into a flesh fly and flew away.