We are new Bee keepers and have def learned a lot of lessons the hard way. We just put a hive top feeder on and had a lot of bees drown it it as they came in from the top and drown. I was quite upset my husband had the idea to put some screen over the feeder under the inner cover and no more drowned bees!!!! WE do have some mold on the bottom of the outer cover I will clean with hot water and try adding some vinegar to the syrup. maybe I will try the popsicle sticks too.