Cathy, swarm cells are queen cells made specifically for swarming. . .it's kind of our warning sign of the hive's intentions! They are usually located along the bottom of the frame so you need only to tip the box and look from the underside to see if your girls are planning on moving! Some people remove them to discourage swarming but I don't think that works--only leaves the hive with no substitute queen! I've found checkerboarding to be the best bet so far for preventing swarming.