Which pest is suspected due to large circular patches of dead grass near sidewalks or curbs, with grass in dead areas pulling easily and brown, sawdust-like frass in the root zone?

• A. European chafer
• B. Hairy chinch bug
• C. Ants
• D. Bluegrass billbug

Answer: (D)

Bluegrass billbug is the pest that fits this pattern. The key clue is large circular patches of dead turf that tend to appear near sidewalks or curbs, where turf often gets stressed from heat, drought, or irrigation patterns. The telling sign is the brown, sawdust-like material in the root zone—frass produced by the larvae feeding inside the roots. When you lift the dead turf, you’ll find roots that are damaged and may reveal the larvae or the characteristic frass in the crown area. The larvae feed on bluegrass roots, weakening the turf until the patches die and lift easily.

Other pests don’t match all of these signs. European chafer can cause root damage and patches, but the combination of circular patches near hardscapes with visible brown sawdust-like frass in the root zone is more characteristic of billbugs. Hairy chinch bugs cause wilt and stippling in hot, dry conditions rather than distinct circular patches with root-zone frass. Ants may disturb turf, but they don’t produce the root-zone frass pattern or the same patch type associated with billbug feeding.