Rose chafers

Identification. An adult rose chafer is a moderate-sized insect, measuring between 5/16-inch to almost 1/2-inch in length. It’s a slender beetle, pale green to tan in color with reddish‑brown or orangish spiny legs. It has short, lamellate antennae, i.e. a series of flat plate- or page-like segments. A rose chafer sometimes resembles a wasp when it’s flying.
The larval stage is called a grub and has a brown head and conspicuous legs. Like other grubs, it’s body is bent into a ‘C’ shape. Fully grown, a rose chafer larva is about 3/4-inch long. Rose chafer larvae are rarely, if ever, seen.
Life cycle. Adults emerge from the ground in late May and early June. Because the rose chafer prefers sandy soil to lay eggs, plants located on sandy sites are most likely to be attacked. Adult beetles feed on plants for three or four weeks, generally until late June. Females lay eggs in the soil, then die shortly afterwards.
Two to three weeks later, the eggs hatch into small, white grub‑like larvae which feed on the roots of grasses and weeds. The larvae spend the winter in the soil below the frost line. They pupate the following spring and then emerge as adults. There is one generation a year.