If you notice that parts of your lawn are beginning to die, you may have grubs. Lawn grubs live in the soil and get their food from the roots of your grass. If the roots are not getting the nutrients they need, the grass begins to dry up and die. The only way to save your lawn is to kill the lawn grubs. One method you can use to get rid of lawn grubs is to use milky spore disease.
Map out your infected lawn in squares that are 4 feet by 4 feet.
Sprinkle 1 tsp. of milky spore disease over the grass in every patch. You only need 10 oz. for every 2,500 square feet of space.
Water the lawn with your hose to get the spores to soak into the soil. The grubs will then be able to eat the spores, which will infect and kill them. It may take a while for all the grubs to die.