Trying here as a last resort. This fuzzy material I find quite frequently on the underside or side of logs where polypores are growing. I first tried mushroomobserver.org but it was suggested there that I try here, with one person saying they often see this associated with Stereum fungi. Is it possible this is bug related?

Edit: I found 5 logs with copious amounts of this soft fuzz this morning. After carefully pulling back the fuzz I found beetle larvae underneath the fuzz on all 5 logs. On a 6th log with a couple of clumps of black fuzz I found cast off beetle skin underneath. Pictures to come, I think platydema larvae.