Later, irregular patches die and can be lifted up or rolled back like a carpet. Grub feeding can make the ground feel spongy. If you have had white grub problems before or suspect you have them this year, begin looking in mid-May by using a cylindrical bulb planting tool to extract a core of lawn so you can examine the roots. Pay particular attention to spots that look unusual. Pay special attention to drainage and compaction.
Healthy lawns can recover more easily from white grub damage.
Merit works best when grubs are small and may require up to 2 applications to ensure season-long control. This material has a low acute toxicity for mammals. Don't treat late in the season when you find dead patches of turf. By this time grubs have done all their damage for the season and are ready to stop eating. Treating now is fruitless.