Billbugs

Pest Description

• bluegrass billbug, hunting billbug, Rocky Mountain billbug and Phoenix billbug
• adults: vary in size from the bluegrass billbug (3/16 – 1/4 inch) to the Rocky Mountain billbug (3/8 – 1/2 inch); brown, reddish brown, or black with a prominent snout
• larvae: legless and cream colored with a brown head

Host Plants, Diet & Damage

• primarily cool season turf (Kentucky bluegrass, ryegrass, fescues, bentgrass)
• can affect warm-season turf (zoysiagrass, St. Augustinegrass)
• patchy brown turf which converges to larger patches

Biology, Life Cycle & Damaging Life Stage

• overwinter as adults with some species also overwintering as late-stage larvae
• adults are active from spring through summer, depositing eggs into turf stems
• larval feeding occurs late spring into summer
• initial larval feeding occurs within the stem; later stages occur in the soil in the root zone
• pupate in soil and emerge as ground-dwelling adults
• typically one generation per year
• larvae are the damaging stage; adults have been shown to cause damage to turf in other regions of the U.S.

IPM Recommendations

• Monitor adult activity with pitfall traps and larval presence by tugging on grass blades.
• Avoid drought-stressing turf, which favors billbug activity.
• Select resistant and endophyte-enhanced turf varieties.
• Apply a preventive insecticide (anthranilic diamide; neonicotinoid) to suppress populations in early spring.

For more information, see our Billbugs fact sheet.