Surface/Soil Feeders - Billbug

BILLBUG
aka: Bluegrass billbug
scientific name: Sphenophorus parvulus
Similar species: Hunting billbug

FIELD KEYS
Hosts: bluegrass, ryegrass, fescues
Site symptoms: Wilted turf that doesn't respond to water, turns brown in spots in June through August near walks, drives, or near trees or shrubs.
Plant symptoms: Grubs hatch inside leaf stems where they feed. Older grubs exit stems to feed at crowns. Sawdust-like frass can be found at base of plants.
Site keys: Sunny locations near trees/shrubs with litter/mulch at base and areas with reflected heat - drives, walks, or buildings.

SPECIMEN ID
Immatures are small, legless, white grubs with brown heads that can reach 1/3 inch. Adults are narrow football-shaped brown to black, 1/4 inch beetles with a downward-pointing snout that has two angled antennae near its base.

SCOUTING TIPS
Adults are often seen crawling on warm walks or drives in early to mid-spring. Look for damaged areas near trees/shrubs with litter/mulch at base and in areas of reflected heat - walks, drives, and buildings. Damaged stems at these locations will easily pull away from crowns and may show exit holes and hollowed stems. Look for frass at the base of damaged plants on soil or in top of thatch. In off-season look for over-wintering adults in litter/mulch at the base of trees/shrubs. Use soap or insecticidal flushes to dislodge adults in season on turf.

CONTROL STRATEGIES
Cultural: Replant or overseed with resistant species/varieties. In bluegrass stands use fine leafed bluegrass varieties if disease is not a problem. Where disease is a problem, use high-endophyte ryegrass varieties instead. Remove litter or mulch from over-wintering locations.

Chemical: Scout for adults at over-wintering sites in late winter-early spring and vulnerable turf site areas in early to mid-spring paying attention to adjacent flat areas that show heat buildup early in the year. If chemical control is necessary, both the grub and the adult stages can be treated but at different times - adults before soil surface temperatures reach 75°F and grubs when soil surface temperatures exceed 75°F.
Growth stages: egg - grub (several instars)* - pupa - adults*
* - treatable stages

Life cycle: 1 year cycle
Sequence: adult - egg - grub - pupa - adult