Turfgrass - May/June Beetle Grubs
(May beetle or June beetle) grubs require three years to complete their life cycle
. Adult May/June beetles are larger than masked chafers (5/8 to 7/8 inches) and range in color from tan to brown to almost black. Adults emerge from the soil in May and June and fly around lights at night. While adults do not attack turf, they do feed on foliage of a wide range of trees, shrubs, and other plants. Eggs are deposited in the soil and hatch in 3 to 4 weeks. Small grubs feed on grass roots during the first summer, moving down in the soil profile with the onset of cooler fall temperatures. Grubs return to the upper root zone in April or May, actively feed throughout the second growing season, then again move deeper in the soil to overwinter. In the third year, Phyllophaga
grubs return to the root zone and feed until May or June, when they enter the pupal stage. Adults develop from the pupae late in the summer, but remain in the soil until the following May or June, which completes their life cycle.