Kill grubs with dish detergent by adding 1 cup of the detergent to equal amounts of mouthwash and water and 2 cups of lemon juice. Place the mixture in a spray bottle and apply to the plants and lawn where you find grubs. Increase the potency of the mixture by pouring 1 cup of boiling water over 1 teaspoon of chewing tobacco. After the water cools, strain the mixture, and add it to the dish detergent solution.
Grubs cause brown patches in lawns. Test for their presence by cutting a square in the sod using a flat blade spade. Remove 3 inches of the soil beneath the sod, and place it in a container. Sift through the soil, and count the number of grubs present. Replace the soil and sod, and then water it well. Repeat the test in several areas of the lawn.
Spray the grass, plants and bases of trees in any areas where you find three or more grubs with the solution. Pour any excess solution around the base of the trees. Spot the plants with the solution as long as you continue to find grubs in the soil. Water the lawn after applying the solution to move it into the soil where the grubs live.