Minecraft wiki entry for Honey_farming, associated text: Observers are less useful here, because they output a signal every time the honey level of the hive changes, not just when the hive is ready to be harvested. This is a problem if trying to collect honey bottles: If the hive is not ready to be harvested, the dispenser ejects a glass bottle when the observer activates it. This could lead to a lot of glass bottles being lost if you don't have a system to pick them back up again. Observers work better for harvesting honeycomb — if the hive isn't ready, dispensers don't wear down the shears or eject them.