A white grub is the immature (larval) form of a scarab beetle. In NY, these include four native species (black turfgrass ataenius, green June beetle, May or June beetles, northern masked chafer) and four introduced species (Asiatic garden beetle, European chafer, Japanese beetle, Oriental beetle).
Grubs live in the soil, feeding on plant roots, so you may not be aware of them until you see damage. While the adults of some species feed on and are damaging to ornamental plants (e.g., Japanese beetle, Asiatic garden beetle), the adults of other species may not feed at all (e.g., European chafer). No adults feed directly on turfgrass.
A Grub’s Life: Egg to Beetle
Knowing the life cycle of grubs is the key to determining whether you have a problem, what to do about it, and when to do it. By considering a grub’s life cycle, you can anticipate problems before your lawn is ruined—not just by root damage, but by hungry birds and rodents as well. The biology of the Japanese beetle is typical of most grubs encountered in New York State and is illustrated below.