Probably the most common incidence of rolling is when a frame of bees is removed from a box when there isn't enough room to do it. The faces of combs are not flat, so when a comb is taken out of a box the gap gets wider, then narrows, so there isn't enough room for the comb and two lots of bees. If the comb is forced, the bees get pinched and rolled. This can make even the most docile colony become angry.