There are two rooms I just don't manage to complete:
North one, East two:
The one with two columns of bug mothers, the one on the right is a single column, the one on the left is a double-column. Those bugs just multiple faster than I can kill them!
Also, the other room is North two, west one:
There are some bugs in a breakable-floor maze, and I can't reach some of them without being stuck for the level. I tried to somehow make them move from the place they are hiding in to a place where I can reach them but failed.
Sorry for not posting this in the solution forum, but it does not allow me to choose the rooms I want to show.