Dishwashing detergent falls into the category of soaps in regard to insect control in the yard. For over 100 years, soaps have been used as a home remedy to control a variety of insects causing damage to a lawn, landscape or garden. Properly mixed and applied, detergent is an effective means of control for some insects including grubs, which are the larvae of the Japanese beetle.
Remove the lid from a 1-gallon garden spray tank. Pour 1/2 gallon of water into the tank.
Add 5 tbsp of liquid dish detergent to the 1/2 gallon of water in the tank. Place the lid on the tank and shake to mix. Remove the tank lid once again.
Add another 1/2 gallon of water to the spray tank, place the lid on the tank and shake to completely incorporate the detergent and water.
Choose a time in early morning or late evening when the dew point is higher and the solution will not dry as quickly as during midday. Adjust the nozzle on the end of the spray wand to a wide spray pattern.
Spray the soapy solution onto the lawn, concentrating on locations where grubs are known to be active. Apply an even spray of the solution to the lawn.
Aphids, mealybugs, psyllids and spider mites are also susceptible to soaps, according to the Colorado State University Extension.