Green June Beetles are part of the family, Scarabaeidae, the Scarab Beetles. These beetles can cause a lot of damage to fruits of several kinds and will feed on the sap of oak, maple and other trees, and on the growing ears of corn.
These are large, robust beetles measuring 3/4 - 1 inch in length by about 1/2 inch wide and therefore quite noticeable when they are swarming as they were on this day.
The white larvae are about two inches long when mature and overwinter underground.
Live larvae are easily distinguished from other white larvae by their habit of crawling on their backs.

Northwest River Trail
Lancaster County, PA