On drought-stressed turf, populations of nine or more grubs per square foot can produce visible injury. Higher grub populations can be tolerated on more vigorously growing turfgrass. These are the largest of the white grubs. Most injury by these Insects occurs along the Eastern Plains, particularly in the southeast area of the state. Adult beetles emerge during May and June and lay eggs in the soil.
Grubs feed during the summer and move deep in the soil to overwinter.
Grubs return to the root zone and feed throughout the following summer. May and June beetle grubs cause most injury during this second season of their life cycle. During spring and early summer of the next year, the grubs complete development, cease feeding, and turn into pupae and adults that remain inactive in the soil. Adult beetles emerge next season. Because of their large size, lawn injury by May or June beetle grubs can occur from populations of five or fewer grubs per square foot.