While there are a great many species in the genus very few are pest problems. Of the 100 species in Texas, for example, only Phyllophaga crinita poses serious problems for turf. Seven different species are pest problems in the Northeast. Adult beetles feed on a wide variety of ornamental trees and shrubs as well as fruit trees. Oak trees seem to be preferred host plants, while adults of some species will also feed on the blades of grasses. Peak emergence of these beetles is often in May through June, as their common names suggest. Life cycles require from 1 to 4 years to complete, with 3-year cycles the most common for our pest species. The larvae may move up and down in the soil periodically during the year to coincide with winter temperatures or hot and dry summer temperatures. Winters are spent deeper in the soil as either second or third instar grubs. Roots of grasses are the preferred foods of larvae, and bluegrass turf is often badly damaged by their feeding.
Residual contact insecticides can be applied to plants the adults gather on to kill them before they have the opportunity to mate and deposit eggs. Adult beetles normally feed at night. Contact insecticides can be applied to turf to kill the larvae, timed to when the larvae are feeding in the root zone of the turf grasses. Granular insecticides can be very effective once watered in to move the active ingredient into the soil.