Billbug

Description: Billbugs are weevils that have the snout, head and thorax about as long as the wing covers. Adult billbugs are dull gray to black or brown beetles  with a snout or bill. The larvae are white, humpbacked grubs with a yellow to brown head. Though there are about a half dozen species that may be found in turfgrasses, only a few cause damage in any given region. The most common pest in Georgia is the bluegrass billbug though the lesser billbug, S. minimus Hart, is somewhat common. The adults are only 1/4- to 3/8-inch long and dark grey to black. They may be covered with a tan or brown coating of soil. The larvae are white with a brown head and look like legless white grubs.

Damage: Symptoms are irregular patches of dead grass, especially near sidewalks or curbs. The dead grass pulls out easily and has hollow stems. The larvae are present under the grass and brown sawdust-like frass is present in the root zone. The adults can be found in the grass near the dead areas.

Billbugs are one of the most difficult turfgrass insects to control. The adults are well armored and do not ingest insecticide while penetrating a grass stem during feeding. The grubs spend much of their lives boring inside grass stems where they are protected from insecticide sprays. However, adults are easier to control than the grubs because they feed on top of the soil where they are more easily contacted by insecticides. Unfortunately, most people don't notice them because they do not cause significant turf damage.

Control: Start looking for the adults when the surface of the soil approaches 65 to 68 degrees F. They will often be seen crawling on sidewalks at this time. Spraying for the adults is normally done in late April to May. Grub damage is often first seen about mid-July. The effectiveness of control is dependent on whether the insecticide reaches the billbugs. If larvae are still inside the stems or if they are deeper than the insecticide reaches, the chemical will be ineffective.