Eggs are deposited by adults in the soil and hatch in a few days. Small grubs feed during the first summer, moving down in the soil to overwinter. The second summer they feed vigorously, casing severe damage, then move down in the soil profile to overwinter the second winter. They complete feeding the third year, overwinter as adults and emerge the following spring to complete the life cycle. Early symptoms include wilting and tan discoloration similar to moisture stress.
Dead patches are small at first, but enlarge as grubs grow and expand their feeding sites.
Turf may die as a result of the destroyed root system unless soil moisture is maintained to encourage regrowth from the crowns. It is possible to check grass for 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 or June beetles are 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 by slicing a square from the turf with a knife or spade and pulling it up.