#2
Dima, I think this is most likely to be a sciophiline mycetophilid. (Using a comination of the type of host fungus, the mucus threads and the anatomy of the larva.)
It would be good to get a more informed opinion, and perhaps a genus name, so that the image can be posted in the gallery.
#5
The last time I checked the contents they (the larvae) were still there Chen, but now fungi are covered with a lot of mold despite it's rather dry and there's enough air, so I'm not sure if I get some results.