Question
How do you get rid of ants nests in lawns without damage to the grass?

Answer
Good Morning Terry:
The 'Lawn Ant' nests in well-drained, clay or gravelly soil and makes the well-known small anthills with a central entrance. Workers are about 1/4 inch long, yellowish in color occurring in lawns, golf courses, pastures, under walks or stones. The most important step in ant control is to locate the nest and destroy the colony.
There are literally hundreds of insecticide formulations labeled for ant control. Some are labeled for general use (homeowners) while others are restricted use (licensed pesticide applicators only).
Sprays or dusts, applied directly in the ant mounds and around the area a few feet, will eliminate the problem. If needed, repeat the application according to the label directions and safety precautions. Diazinon, Baygon, carbaryl (Sevin), and bendiocarb (Ficam) will kill ants.
In many cases, once an ant infestation has been found, control measures are best accomplished by a licensed, professional pest control firm.
If the ants begin to enter the house, use a perimeter spray, treating the foundation as high as two feet and out three feet into the soil, especially around windows, doors, etc. with the insecticide mixed in water, preferably as a wettable powder formulation, to avoid plant injury. Diazinon or Baygon give good control.
Try to mow the grass to a height of 2 ?to 3 inches and mow frequently cutting no more than 1/3 of the grass blade at each mowing. This will give you a more dense turf and will discourage the ants from nesting.
Have a good lawn!
Floyd McMahon