White grubs are the larval stage of a group of beetles collectively known as scarabs (Family Scarabaeidae). While there are many different species of scarab beetles in Nebraska, the larvae of only a relative few cause significant injury to turf. Among these are the masked chafers, Cyclocephala spp. (annual grubs); May/June beetles, Phyllophaga spp. (three-year grubs); the black turfgrass ataenius, Ataenius spretulus, and most recently the Japanese beetle, Popillia japonica.
All white grubs are similar in appearance with cream-colored, C-shaped bodies, reddish-brown heads and three pairs of short legs immediately behind the head. When fully developed, they range from 1/4 to 1 inch in length, depending on the species. Identification of the different groups of white grubs is possible by examining the arrangement of hairs and spines on the raster area on the underside of the terminal abdominal segments. These patterns can be distinguished using a small hand lens. The arrangement of spines on masked chafer grubs is random with no clearly defined lines, while spines on May/June beetle grubs are arranged in two distinct parallel lines. Japanese beetle grubs are characterized by a pattern of rastral spines arranged in a "V" shape, whereas the black turfgrass ataenius is distinguished its small size and pad-like structures on the end of the abdomen.