Wasp or fly larvae

5775  These larval sacks were protected in some fine insulating substance just like wool. Found them in a junction box on a wall outside.  (It even smelled like lambs wool.)  There were about ten of these brown, slightly crispy-shelled sacks.  Only one sack contained a set of 30 or so active larvae, the rest were nearly all milky, yellowish/white liquid. We’re in the Portland, Oregon, U.S. area. Really curious and unusual.  Can anyone help? Barrett and Susan.

This is another head-scratcher; I am unable to determine to my satisfaction whether these are wasp or fly larvae. If at all possible, can the contributor provide any image(s) of the sack-like structures before they were cut open? Ed Saugstad, retired entomologist; Sinks Grove, WV.