If you purchased hives coming up from southern states...you might find SHB (Small Hive Beetle). SHB will usually die off over the winter because they cannot penetrate below the frost line in Colorado to reproduce; however, if you'd prefer to get rid of them before then, this device can help. Fill the center reservoir with apple cider vinegar (bait) and the outer reservoirs with mineral oil or cooking oil. Hang on an outside frame. Empty weekly.