The hunting billbug is a small weevil that feeds on warm-season turfgrasses, particularly zoysiagrass and bermudagrass. Adults are 8 to 11 mm long, reddish-brown to black, with the distinctive long snout common to weevils. If your lawn has mysterious dead patches that showed up in late spring or summer, this insect may be the cause.
How to Identify Hunting Billbugs
Adult hunting billbugs look like small, dark beetles with an elongated snout (or “beak”) that curves slightly downward. They range from reddish-brown to nearly black. You can distinguish them from other billbug species by the markings on the plate just behind the head and on their hardened wing covers. They’re slow-moving and often play dead when disturbed, so you might mistake one for a bit of debris on the sidewalk or driveway.
The larvae look completely different: white, legless grubs with a brown head, measuring 7 to 10 mm at their largest stage. You’re unlikely to spot larvae unless you actively dig into damaged turf, because they feed inside grass stems, crowns, and roots.
Life Cycle and Seasonal Activity
Hunting billbugs go through complete metamorphosis: egg, larva, pupa, and adult. They typically overwinter as adults, though large larvae can survive the winter too. As soil temperatures warm in spring, overwintered adults become active, begin feeding on grass stems, mate, and lay eggs.
Females deposit creamy white, oblong eggs that hatch in 3 to 10 days. The larvae then feed inside turfgrass stems, working their way down into the crown and root zone over a period of 3 to 5 weeks. After pupating for just 3 to 7 days, new adults emerge and the cycle repeats. Multiple overlapping generations can occur from spring through fall, with activity slowing as temperatures drop.
What Hunting Billbug Damage Looks Like
Damage from hunting billbugs is easy to confuse with drought stress, disease, or other insect problems. In areas where overwintered larvae are present, you may notice delayed green-up in spring: patches of turf that stay brown longer than the surrounding lawn. This alone can be a useful early clue.
The first obvious signs of active feeding usually appear by mid-June, when individual grass plants start dying from larval feeding at the crown. Early damage shows up as small dead spots roughly 2 to 3 inches across. Left unchecked, these spots merge into large, irregular patches of dead turf that can ruin an entire lawn area. Unlike some related species, adult hunting billbugs at high population densities can also cause visible damage just from feeding on stems and leaves, even before larvae become the main problem.
The Tug Test: Confirming Billbug Damage
The simplest way to check for hunting billbugs is the tug test. Grab a handful of dead or yellowing grass stems at the edge of a damaged patch and pull. If the stems break off easily at or near the soil surface rather than pulling up with roots intact, look closely at the broken ends. Billbug larvae leave behind a fine, powdery, sawdust-like material called frass inside the hollowed-out stems. This frass is the definitive sign of billbug feeding. No other common turf pest produces it.
In warm-season grasses like zoysiagrass and bermudagrass, you should also inspect the stolons (above-ground runners) and rhizomes (below-ground runners) for the same hollowing and frass. The best window for this inspection is June through August, when larval feeding is most active.
Which Grasses Are at Risk
Hunting billbugs primarily target warm-season turfgrasses. Zoysiagrass is especially vulnerable, with larvae hollowing out individual shoots from the inside. Bermudagrass is also a common host. Kentucky bluegrass can be affected as well, though it’s more commonly damaged by the closely related bluegrass billbug. If you have a zoysiagrass lawn in the transition zone or southern states, hunting billbugs should be on your radar as a potential pest every year.
Managing an Infestation
Timing is everything with billbug control. The most effective window for treatment is in spring, when overwintered adults are active on the soil surface but before they’ve laid eggs and larvae have burrowed into stems. Once larvae are feeding inside grass tissue, they’re protected from most contact treatments.
Preventive insecticide applications target adults as they move across the turf surface in spring. Systemic products, which are taken up by the grass plant itself, can also reach larvae feeding inside stems and crowns. Your local extension office can recommend specific products labeled for billbugs in your state, along with the best application dates for your region. Soil temperature is a more reliable guide than calendar date, since billbug activity tracks warming soils rather than fixed months.
Curative treatments later in summer are less reliable because larvae are hidden inside plant tissue and damage is already done. Even if you kill the insects at that point, the turf still needs to recover or be reseeded.
Cultural Practices That Help
A healthy, well-maintained lawn tolerates billbug feeding better than a stressed one. Proper irrigation keeps grass plants vigorous enough to outgrow moderate feeding damage, and it encourages the deep root growth that gives turf a buffer against crown injury. Reducing thatch buildup is also useful, since thick thatch layers provide shelter for overwintering adults and make it harder for any applied treatments to reach the soil.
If you’re establishing a new lawn or renovating damaged areas, choosing cultivars with documented billbug tolerance can reduce problems long-term. Endophyte-enhanced varieties of certain cool-season grasses, for instance, contain naturally occurring fungi that deter billbug feeding. For warm-season lawns, ask your local extension service which zoysiagrass or bermudagrass cultivars perform best against billbugs in your area.
Entomopathogenic nematodes, microscopic roundworms that parasitize soil-dwelling insects, offer a biological control option. These are applied as a drench to the turf and work best when the soil is moist and larvae are present near the surface. They won’t eliminate a heavy infestation on their own, but they can reduce billbug populations over time as part of an integrated approach.