The difficulty of the wasps increase as you go further into the dungeon. If the swarm appears dense it is more dangerous. They might seem quite harmless, but they can actually be one of the harder enemies in the game.
If you force attack shopkeepers with your wasps there's a chance you can bait out all charges from the wand of the shopkeeper.
Zapping wasps with a wand of polymorph displays the message "The wasps look slightly different." The result changes the number of wasps in the swarm, affecting their overall deadliness. Therefore, this action is ill-advised early game, but it's a considerable strategy later on.