Adults, which range in size from 6-13mm in length, feed, mate, and lay eggs in late May or early June.
Adults feed on stems and the undersides of leaves.
It is possible to distinguish this damage from that of the larvae, which chew holes in leaves and may completely defoliate a plant during their development if they are numerous. Larvae can occasionally be found feeding among florets. Although generalists as adults, these beetles were exceptionally common on wild sunflower during the 2000 field season. They were observed feeding en masse on sap at holes that they gouge from sunflower stalks. These june beetles are encountered commonly at our field site, and during the summer of 2000, male and female beetles were observed feeding on small drought-stressed H. annuus .