These flights occurred over two peaks in mid-June. Computer models and field sampling calculate that now is your best chance to treat lawns known to have white grub problems. The Texas Agricultural Extension Service recommends checking for grubs before deciding to treat. Dig small holes, three to four inches deep, in several places around the yard. Grubs found during this target treatment period should be small, less than the length of a thumbnail.
Treatment is necessary only when more than four or five grubs are found per square foot of turf.
Most homeowners don't have grub infestations serious enough to treat. But if you've had problems with grubs in the past and find high numbers in your lawn, you will want to treat now for the best control. Not all brown spots in lawns are caused by insects. Lack of water and some turfgrass diseases also cause dead spots. To be sure, try tugging at the grass in the brown area.