Annual bluegrass weevil (ABW) has been a significant turf pest in the northeastern United States for several decades. Since the mid-1990s, it has expanded rapidly into the mid-Atlantic, Midwest and parts of the Southeast.
Turf managers growing creeping bentgrass and annual bluegrass in areas where ABW was not previously a concern should be vigilant. Before this summer, the Kansas City area had reported only a few isolated cases of ABW damage. This summer, however, several local golf courses with creeping bentgrass tees, fairways and closely mown green surrounds containing annual bluegrass experienced notable ABW damage.
Effective identification and treatment depend on population scouting and a strong understanding of ABW biology and life cycle. ABW overwinters as an adult in the top 2 inches of the soil, often under leaf litter or in tall grass areas, then moves into closely mown turf in early spring. After egg hatch, larvae progress through five instars. The first three feed inside the plant stem, while later instars exit into the soil and feed on the crown.
Preventive chemical applications without a history of ABW damage or scouting-confirmed populations are not recommended because ABW can quickly develop resistance to adulticides, especially pyrethroid insecticides. Active scouting is essential for assessing populations and selecting the appropriate control product and application timing. Linear pitfall traps, soap flushes, examining clippings or vacuuming playing surfaces are commonly used techniques to scout for adults in spring, while exposing turf core samples to heat or submerging them in saline solution is often used to detect larvae.
Control is further complicated by ABW’s ability to produce two or three generations per year, which can overlap, so you may have multiple stages of ABW present at the same time. Phenological indicators such as forsythia and rhododendron bloom can help time scouting for the first generation of adults and larvae, but they are ineffective for tracking later generations.
Research continues to explore potential biological controls for ABW, but chemical control remains the primary tool for achieving the level of control required for effective management on golf courses. Several adulticide and larvicide options are available – including newer chemistries – but choices remain limited and resistance management should be a key consideration in both preventive and curative programs. Although ABW prefer to feed on annual bluegrass, it’s worth noting that damage to creeping bentgrass has occurred in southern portions of the insect’s range.
For more detailed guidance on ABW and scouting timing, read the USGA Green Section Record article “Best Management Practices for Annual Bluegrass Weevil Control in Golf Course Turfgrass” or reach out to your regional USGA agronomist.
Central Region Agronomists:
Zach Nicoludis, regional director, Central Region – znicoludis@usga.org
Tom Gould, agronomist – tgould@usga.org
Steve Wilson, agronomist - swilson@usga.org
Information on the USGA’s Course Consulting Service
Contact the Green Section Staff