These grubs are plump, C-shaped insects with three pairs of legs. They are whitish with dark areas near the rear. They have a distinct, brown head. The adults are beetles commonly referred to as chafers, May beetles, June beetles, Japanese beetles or green June beetles. They occur throughout the state of Georgia.
Grub feeding destroys roots, leaving the tops to wither and die. In heavy infestations, roots are pruned off to the extent that turf can be rolled back like a carpet. Symptoms of grub damage include yellowing or browning of the grass and signs of drought stress when moisture levels are good. Grass may feel spongy when infestations are heavy.
Adult billbugs are weevils 1/5 to 3/4 inch long. The reddish-brown to black adults have a pair of jaws at the tip of a long snout or "bill'. The young are white, legless grubs about 3/8 inch in length with the rear end wider than the head. The "hunting billbug" is the most common type found in Georgia. It occurs throughout the state.
Zoysia grass and Bermuda grass are most often injured, but feeding may occur on many grasses. When infestations are heavy, roots of grass are destroyed and the turf is killed in irregular patches. Early damage resembles dollar spot disease in small spots of dead or dying grass. The most damage occurs in June and July. Damage from billbugs differs from white grub or mole cricket injured turf in that infested soil usually stays firm.
Sod webworms are caterpillars of small brown to dull gray moths. Webworms grow to a length of nearly 3/4 inch and vary in color from pinkish white to light green to yellowish brown with a light to dark brown or black head. They are covered with fine hairs. The moths have a wingspan of about 3/4 inch. They fold their wings closely about their bodies when at rest and have a prominent forward projection on the head. Sod webworms are found throughout Georgia.
Damaged grass blades appear notched on sides and are chewed raggedly. Irregular brown spots are the first signs of damage. Large areas of grass may be damaged severely, especially under drought conditions. A heavy infestation can destroy a lawn in only a few days. Damage tends to become visible in mid to late summer and in highly maintained lawns. Sod webworms are partial to newly established lawns. Favored turf types are Bermuda, Centipede, and Bahia, Zoysia, and St. Augustine grasses.
Mole crickets are light brown, up to 1 ½ inches long, have short, stout forelegs, spade-like feet, and large eyes. The young resemble the adults except that they are much smaller, have no wings, and are sexually immature. Three species occur in Georgia. Two, the tawny mole cricket and the southerh mole cricket, are pest species. Mole crickets occur primarily in the sandy soils of the Coastal Plain.
The most damaging species of mole crickets feed on grass. Other species don't feed directly on grass, but their tunneling activity damages turf. Both young and adults burrow beneath the soil and make tunnels similar to, but much smaller than, those made by moles. This loosens the soil and causes it to dry out quickly. It also clips the roots of the grass plants. Left unchecked, mole crickets will build up in an area and completely destroy the grass, leaving bare ground.