Cockroaches are on 2 different episodes, and are #6 on Survivors, and #1 on Global Conquerors. If cockroaches are our worst nightmare, then rats are what cockroaches have bad dreams about. They have taken over the world, and are multiplying fast. They can survive two hundred times more radiation than humans can. However, at the end of the experiment trying to get rid of them, the lab was left with radioactive cockroaches. The only way to get rid of them is to hit them with a hammer. Even then, they could live for a month, and only then die of thirst.