Back in July, I discussed the damage white grubs, the larvae of several beetle species, could cause to the root systems of your lawn and the importance of scouting for them. Billbugs are another destructive root feeding insect that we need to be on the lookout for as well. Late-summer weakened lawns and athletic fields that have symptoms of drought stress or disease attack, even though adequate water and preventative fungicides have be applied, could have these small turf feeding weevils and their larvae feeding on them.
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 then feed until they become too 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 are feeding most of the summer, but their 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.
While 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 take a shovel and lift a one foot square section of the turf up including soil to a depth of about an inch, then 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 29, 2011
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