The masked chafers have been flying and laying eggs for most of the month of July. Like other things, they were about one week behind normal in their emergence and activity this year. The eggs hatch in 2 to 3 weeks meaning early to mid-August is the earliest the white grub larvae will be in the soil to begin feeding on grass roots. The damage symptoms that grass plants express because of the root feeding going on in the soil usually do not appear until late August, September or October. Early symptoms include wilting and tan discoloration.
Later symptoms can vary from small discolored patches to large, irregular dead areas.
Return to typical, rainless conditions could change the health of the turfgrass very quickly. It is possible to check turfgrass for white grub damage before it becomes severe and noticeable. First, check your records or memory for the location of damage in previous years. Then consider areas where masked chafers are most frequently seen such as along sidewalks, driveways and streets and at the outside edge of the light thrown by a street light or yard light. Beginning in mid August look for grubs in the soil in these ares by slicing a square from the turf with a knife or spade and pulling it up.