Late summer weakened lawns, or athletic fields with symptoms of drought stress or disease attack, could have small turf feeding weevils and their larvae feeding on them...even though adequate water and preventative fungicides have be applied.
Adult billbugs are hard bodied, usually grayish or black, 1/4 to 7/16 inches long, and have long beak-like snouts with chewing mouthparts at the tip. Billbug larvae are small, 3/8 inch or less, cream colored legless grubs with yellowish brown heads.
The adults will deposit tiny eggs into the stems and crowns of the turf plants where the young larvae feed until they become large, then move into the thatch where they continue to feed on stolons, rhizomes and roots.
While zoysia and hybrid Bermudagrass lawns are most often preferred, they will also feed on Bahiagrass, centipede, and St. Augustine lawns. The adults and larvae have been feeding most of the summer, but the symptoms get more pronounced near the end of summer as turf growth slows, along with hot, dry conditions.
As cooler weather approaches in the fall the adults will begin to seek sheltered sites in which to overwinter. The best management for control is to apply a preventative insecticide in the spring prior to egg hatch. Conventional soil insecticides can be applied in the spring or fall to kill adults and larvae feeding on crowns, stolons, and roots.
To scout for their presence use a shovel and lift a one foot square section of the turf and soil, including soil (depth of about an inch). Closely examine the turf roots and soil for larvae and chewed and broken turf stolons.
For more details on billbugs and other turf feeding insects and their control refer to Extension publication #2331 “Control of Insect Pest in and Around the Home Lawn.”
Published August 30, 2010
Dr. Wayne Wells is an Extension Professor and Turfgrass Specialist. His mailing address is Department of Plant and Soil Sciences, Mail Stop 9555, Mississippi State, MS 39762. firstname.lastname@example.org