Interesting, because I tried smaller cells this past winter and got 100%
survival. But a friend who also tried the smaller cells did about
normal.  We did it because of the guess that the brood cycle would be
shorter and hence less varroa. Seems we were right, but I did so many
other things, like taking honey off early, putting all new frames with
the smaller cells and putting patties in high and low for winter that
there is no science in the cells being the cause for the success. Just
take your pick.
Bill Truesdell
Bath, ME