Pest drones are a special kind of pest. They are only encountered in the quest The Void Stares Back, after being summoned by Wizard Grayzag. Two of them will attack Korasi, and, if you choose to save Jessika, they will kill Korasi. Numerous pest drones are seen shortly afterwards during the fight with the Pest Queen.
During the fight, they will not attack, but they will heal the queen. Each drone has 1000 life points, and they can only be killed by Void Knight archers, which is why it is important that the player keeps the archers alive. The first time the drones spawn during the fight they will be in a group of four. A group of three drones will spawn shortly after the first group has been killed. After that two will spawn, and finally a single one; after that, no more drones will appear.
Pest drones are fightable along with the Pest Queen as a class A boss monster in the Dominion Tower minigame if the player has completed The Void Stares Back.