It's not my experience that shb eat bee larvae and I have never read this anywhere. However when a hive begins to get infested w/shb hygienic bees will remove larvae and tear down the comb trying to control the shb. I have come up on a couple of hives that were hauling out perfectly healthy looking brood. I poped the tops to find a infestation of shb.
I have not been able to turn around a hive once it has reached the larva stage inside the hive
! I have frozen combs, placed in traps' and done total shake downs, only to lose the hive later.
Best defense, I have found, try to keep hive strong and the use of traps etc. early to try and control the shb population.