Rats in warehouses: from chewed cables to contaminated stock

How do you know you have a problem?

You will not see the rat itself at first, but the signs are clear enough:

• Dark droppings the size of a rice grain along the walls
• Dark greasy streaks on the walls where they pass again and again
• Gnaw marks on the corners of cartons and sacks
• In chilled stores: footprints in the dust behind the racking

Why is chewed cable so dangerous?

A rat's teeth never stop growing, so it gnaws anything hard to file them down, electrical cable included. The result is bare wire inside a wall or ceiling, and that is one of the leading causes of warehouse fires. What makes it dangerous is that you cannot see the damaged cable, and you may not find it until after the fire.

What about the stock?

Stock is lost in two ways: gnawed directly, or contaminated. In the second case the whole carton has to be destroyed even if only one small corner was touched. That is a double loss.

Food warehouses: why poison is not the answer

Where food is stored, poison is a risk: the rat can die somewhere hidden inside the building and become a source of contamination and odour. The better answer is numbered mechanical traps set along the walls, checked weekly with the results recorded, and that record is normally asked for at any health inspection.

The real fix: close the entry points

Any control programme that does not start by closing entry points will meet the same problem every year. The measurements worth knowing:

• A mouse gets through a gap the width of a pencil
• A rat needs one the size of a coin

The points to check first

The bottom of loading doors, air-conditioning openings, and pipe entries through the external wall. Close them with wire mesh and mortar. Foam on its own is not enough, because rats chew straight through it.