Create a solution made from 1 oz. of liquid laundry detergent, 1 oz. of white vinegar and 10 oz. of water.
Pour some of the solution onto the stain. Tap the area repeatedly with a cleaning brush.
Let the solution soak for 10 to 15 minutes.
Put the rug in your washing machine, along with laundry detergent. Set the washer to a large load setting. This will ensure that the rug becomes completely submerged during the wash. Do not put anything else in the washer with the rug.
Air-dry the rug when it has finished washing. If the stains are still visible, repeat the process until they're gone.