They have swept through Outback towns such as Cloncurry and Julia Creek, eating crops and contaminating water sources.
They are a menace to pets and some domestic animals, including ducks owned by Mr Lord.
He said: “Last night, the ducks were going mad and I went downstairs to see what was going on, thinking maybe there’s a cat in there or something. And there’s bloody lots of rats running through the cages, through the pens chasing ducks. They’re bold as hell.”
In their desperate search for food, some of the rats have been swimming to sandbars in rivers and estuaries.
When the tide rises, they drown, and their bloated bodies wash up on beaches.
Authorities are doing their best to remove the rodent corpses, which attract clouds of flies.
The fishing town of Karumba has been particularly badly hit, where rats have been climbing up anchor chains and onto boats that are moored offshore.