The green June beetle is one of the white grubs that may be found in lawns. This grub is unlike other grubs in that it will crawl on the surface of the grass at night. Other white grubs remain in the soil and feed on the turfgrass roots.
The adult beetle is ¾ - 1 inch long and ½ inch wide. The body is forest green on top, with or without tan stripes on the wings, and the underside is metallic green or gold. The legs have stout spines to aid the beetle in digging. The adults fly during the day and are commonly referred to as "June bug", "June beetle" and "fig eater". The adult beetles feed on thin-skinned fruit and plant sap.
The larvae or grubs, are creamy colored, with a brown head, short stubby legs, stiff abdominal bristles, a wide body and reach 2 inches in length when mature. They have an unusual habit of crawling on their backs. The grubs do this by undulating and using the abdominal bristles for traction. The larvae feed on dead and decaying organic matter and plant roots. Damage to turf occurs as a result of tunneling and root feeding.
Young grubs tunnel horizontally in the top 4 inches of soil, loosening it, eating roots, and thinning the thatch. As the grubs grow, they tunnel vertically and deeper. Tunnels to the surface are kept open by the grubs pushing soil to the surface. This activity results in mounds that resemble worm castings. The holes are about as wide as your finger, while earthworm tunnels are usually the diameter of a pencil or smaller. Fresh mounds are especially noticeable after a heavy rain.
Keep turf from being stressed by providing adequate water, fertilizer, lime, and mowing at 2 ½ - 3 inches. Control is usually not necessary on home lawns.
Adapted from: "Green June Beetle". Lee Hellman and J. Kevin Mathias, Institute of Applied Agriculture, University of Maryland, College Park, MD.