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How to identify it
- Adults are snout beetles about 3.6 to 4.5 mm long that start out mottled tan to black with fine hairs and yellow-brown and gray scales, then turn shiny jet black as the scales wear off.[1]
- Larvae are legless, cream-colored grubs with orange-brown heads, 1/25 to 1/6 inch long and shaped like a grain of rice; the young ones bore inside grass stems.[1]
- Eggs are oblong, pale yellow turning black before they hatch, and laid in a notch the female chews in a grass stem, between the leaf sheath and the stem.[1]
Look-alikes
Where it lives
Its range runs from western North Carolina to Prince Edward Island and west to Ohio and Ontario, with newer detections in Arkansas (2016), Kentucky (2018), Wisconsin and Indiana (2020), Michigan, Nebraska and Georgia (2022), Kansas (2023) and northern Illinois golf courses (2023).[1][3]
Biology and life cycle
Adults overwinter under leaf litter and in tall grass along wood lines next to short-mown turf and walk out to it in spring; forsythia in full bloom marks the start of that movement.[1]
Females lay eggs in notches chewed in grass stems, and the larvae pass through five instars as they feed.[1]
It feeds mainly on annual bluegrass (Poa annua) and also creeping bentgrass mowed to about 1/2 inch or less on greens, tees, fairways and collars.[1][3]
Damage and signs
- Damage shows up from mid to late May on the edges of tees, collars, approaches and fairways and is easily mistaken for dry spots, wilt or anthracnose; it spreads quickly as larvae feed on roots and crowns.[1][3]
- Larval and adult feeding on stems and crowns weakens the roots and kills the plants.[3][1]
Health risk
It feeds on turfgrass; Penn State, NC State and Illinois Extension mention no risk to people.[1][2][3]
Control
Prevention
Home lawns usually need no control: Illinois Extension says lawns with annual bluegrass aren't at risk of damaging injury because they are mowed and managed differently from golf turf.[3]
Traps and physical control
On golf greens, mowing removes many adults in the clipping baskets (35 to 40 percent at a 2.5 mm mowing height in a Penn State study), and heavy rollers and soft-bristle groomers crush more.[1]
Biological control
Parasitic nematodes such as Steinernema carpocapsae applied in late spring can reduce larvae.[1][2]
Pesticides
Insecticides are timed either to adults before they lay eggs or to larvae as they move into the soil; overuse of pyrethroids has produced resistant weevil populations in parts of the Northeast.[1]
Common questions
- Will annual bluegrass weevils damage my home lawn?
- Illinois Extension says home lawns with annual bluegrass aren't at risk of damaging injury, because they are mowed and managed differently from golf course turf.[3]
- How do I tell an annual bluegrass weevil from a billbug?
- It is about a third the size of a billbug, its antennae attach near the tip of the snout rather than the base, and its snout is shorter and stouter.[2]
Sources
- Penn State Extension, “Annual Bluegrass Weevil (updated March 3, 2025).” extension.psu.edu/annual-bluegrass-weevil (accessed 2026-10-19)
- NC State Extension, “Annual Bluegrass Weevil in Turf (AG-408).” content.ces.ncsu.edu/annual-bluegrass-weevil-in-turf (accessed 2026-10-19)
- University of Illinois Extension, “Emergence of a new Illinois turf pest: The annual bluegrass weevil (Pesticide News, September 11, 2024).” extension.illinois.edu/blogs/pesticide-news/2024-09-11-emergence-new-illinois-turf-pest-annual-bluegrass-weevil (accessed 2026-10-19)
- iNaturalist, “Listronotus maculicollis taxon page (order and family).” www.inaturalist.org/taxa/303945 (accessed 2026-10-06)