Ted Fischer wrote that bees never eat brood.
 
This is certainly not my experience.  I can remember in June 1986 sitting in
the University of Minnesota talking with the late Basil Furgala about
cannabilism in bees.  He told us of trials he had done where he had
witnessed cannabilism as a side issue and he stirred my interest in this
subject.
 
When I came back to Australia, I started to take notice of this and there are
times when bees cannabilise brood, especially unsealed brood.  We have an
ironbark called Caley's ironbark which flowers in the winter time.  It
produces a great honey but is pollen deficient.  If it is in any way dry or
there are no wattles flowering to produce pollen, the bees will eat the
unsealed brood and often the sealed brood.
 
There are other times when conditions deteriorate very quickly that bees will
also eat brood.
 
Maybe the conditions in the USA are a lot better than ours and you don't see
it but Basil had assured he had seen it in Minnesota.
 
FWIW
 
Trevor Weatherhead
AUSTRALIA