The best time of year to deal with a grub worm problem is in late summer or early fall. This is when the grub worms are still small and near the surface. After that, it will be a lot harder and take a lot more work to get rid of them.
If you want a fast and strong solution, I suggestion a chemical insecticide. These are products like Dylox, Merit, or Mach-2. Always read the instructions before using any chemical pesticides. For a more natural and less chemical approach, try these other solutions.
Milky spores carry a disease that will kill grub worms. And the best part is that it’s safe for your lawn! Follow the instructions and add a bit of the milky spores to the spots in your yard where the grub worms are causing damage. They will catch the disease, die, and then release more spores into the soil. This is a very effective way to treat a grub worm problem.
Beneficial nematodes are another great solution. You can buy this at most nurseries or local stores, and they come in a few different types. Whichever you get, follow the directions and add them to your yard. Like milky spores, they will kill the grub worms and stop them from infesting your yard.
Mix a bit of neem oil with water and spray it liberally onto the parts of your yard or garden that are getting damaged by the grub worms. Repeat this treatment as necessary, and you will find things improving. Neem oil is a natural ingredient that has insecticidal properties.