Comment by Twinky on Dungeon Odyssey - Chapter 113

The horned rats are sick of beings slaves and or worse snacks for the monster in the labyrinth. In morth (rebel leader) mindset even if the Naga king (MC) treat them better they will always be slaves in life and death. So he decided to revolt and wipe out all the labyrinth lords of 9th floor and the rest of the floor believing that there sheer numbers and tunnel access would prove an advantage. Twitch wanted to end this revolt ASAP to prevent a rat civil war or worse case scenario rat extinction. The manhwa here is half missing check mangageko they have the full chapter!.

It is also interesting to note that the reason for this is that they breed so fast that many of them have never lived under any other nation than the nagas, so to them, this is the worst it has ever been. 

In theory, this culling will probably need to happen fairly regularly, unless MC can devise a way to stop the cycle since in a short time, this exact scenario will occur again... and again... and again...