I had 3 hives going into winter. On a warm sunny day I went to check on them. All were gone. No frozen cluster, just a few random carcases and plenty of honey! Mouse nest in one of them. Also, all old brood combs are black. All three smelled like beer (?). Any ideas? Last year I lost one, but I thought I wintered them improperly and it had too much moisture and maybe dysentery. It gets cold here (-20F) on occasion.
Would appreciate any imput-thanks.