PEST MANAGEMENT
Japanese beetle larvae . Photo by Fred Miller , University of Illinois .
as hard-shelled beetles with a metallic-green sheen to their wing covers . Larvae appear similar to the other white grub species . Japanese beetle grubs hatch from eggs in mid-summer , feeding through July into September . They will burrow deeper in the soil as fall arrives and overwinter until May the next year when they will pupate and mature into adulthood that summer .
Masked chafer adults are normally present from early to mid-summer . They deposit their eggs into the top 2 inches of soil , usually in small clusters . Hatching occurs in late summer , with immediate root feeding to follow . As the larvae proceed through several stages , the potential for damage grows significantly . As temperatures drop in fall , grubs move deeper into the soil to overwinter . As soil temperatures warm in the spring , they return to the active root zone , feed for a brief period , pupate and emerge as adults to begin a new cycle .
May / June beetles require three years to complete their life cycle . The stages look similar to the other species of white grub , but the process of maturing is extended over a longer period of time . Between the first two years , the grub is feeding and growing . By year three , they will pupate in the early autumn , overwintering in the pupal stage and emerging as an adult the next May or June , hence the name .
Japanese beetle grubs . Photo by Jonathan L . Larson , Ph . D ., University of Kentucky .
White grub management is most often predicated upon the use of insecticides . Managers can consider using either a preventive approach or a curative approach . The choice may come down to the need for perfect turf , budgetary reasons or historical problems . Preventive management is the most common choice and insecticides such as imidacloprid , clothianidin and chlorantraniliprole are frequently used active ingredients . Preventive applications occur in the early part of the growing season , usually being applied between May and July . This can appear counterintuitive as the grubs may not be present or not feeding during this window . These insecticides are systemic and will be inside of the turf for the rest of the growing season , killing the future grubs that may be born in the turf . Spraying these chemicals too early may mean that there won ’ t be high enough residues of the insecticide later in the season to provide protection . Going out too
Black turfgrass ataenius . Photo by Jonathan L . Larson , Ph . D ., University of Kentucky .
12 SportsField Management | March 2023 sportsfieldmanagementonline . com