Why do beekeepers use smoke?

From time to time beekeepers need to get inside their hives to perform maintenance, treat for mites, feed their bees, clean up propolis, wax, or take frames out to extract. They use smokers to aid them in this process, like the one pictured below:
Without smoke, beekeeping can be an uncomfortable experience, trust me! Even with a bee suit on, you can get stung! I got stung on my crazy hive a few weeks ago THROUGH my suit, because lets get down to brass tacks: They crazy.
There are two main reasons why beekeepers use smoke. First though, I’d like to dispel the notion that the smoke makes them ‘calm.’ It certainly makes them seem ‘calm,’ I’ll give you that. But what it is really doing is most likely the opposite.
Bees, like other social insects, communicate with each other via pheromones. Bees have a particular pheromone they emit when they feel danger, called the alarm pheromone. Though it sounds like a joke, it smells like bananas. Its not just me. When I was getting into beekeeping, I read that the alarm pheromone smelled like banana oil in a textbook (yes, I bought AND read a textbook….I am a nerd.) that I bought. It sound like an exaggeration, but sure enough, I smelled it distinctly when I first started opening up bee boxes and messing around.
So, if a worker notices a problem, like a big chubby dude messing around in their house (I guess you don’t have to be chubby), she’ll emit that pheromone to alarm the other bees. The other bees will get alarmed, and they’ll try to swarm and sting you. When you use smoke on a hive, it disrupts their ability to communicate via the alarm pheromone. In other words: They don’t get alarmed because they can’t smell the alarm. It’s like somebody shouting in your ear just before the fire alarm goes off. You’re temporarily deaf so you don’t evacuate the building.
The second reason why beekeepers use smoke is when the bees smell the smoke they start making preparations to leave the hive, because of imminent fire danger. The workers start gorging themselves on honey so when they leave and start a new hive somewhere, they have enough stores to make a fresh start. They APPEAR calm, but really it’s like you and me when you gorge on twinkles. You don’t want to move around very much. Though this may sound cruel to the bees, smoking them is actually better than not smoking them. The bees recover quickly from the smoke, and since bees are alarmed have a greater tendency to sting you and then therefore die, less bees are harmed and more are left alive after a hive inspection.