Cecidomyiidae, gall on Lead Plant, larva - Rhopalomyia undescribed-species-on-amorpha
Weaver Dunes, Wabasha County, Minnesota, USA May 12, 2009 Size: 1 mm
larva inside what looks to be a silken case (or maybe hairs from the plant)
I was surprised to see it still alive (it moved). Most of the galls were empty but I've had nothing emerge.