HUNTING BILLBUG

The Hunting Billbug, Sphenophorus venatus vestitus, in North Carolina

Diane E Silcox and Rick L Brandenburg*

The hunting billbug was first described as a pest in 1956 on the zoysiagrass of a Florida nursery. It is one of the most widely distributed and abundant billbug species. The hunting billbug occurs from New Jersey to Florida and through the Gulf into Texas and north to Kansas and Missouri. They primarily feed on zoysiagrass and hybrid bermudagrasses, but will also feed on bahiagrass, centipedegrass, St. Augustinegrass, seashore paspalum, tall fescue, Kentucky bluegrass, perennial ryegrass, and Chewings fescue. Non-turfgrass host plants include nutsedge, crabgrass, signal grass, barnyard grass, wheat, corn, sugarcane, and leatherleaf fern. In North Carolina the hunting billbug primarily feeds on zosiagrass and bermudagrass. Research efforts at North Carolina State University include biology and ecology of the hunting billbug in North Carolina as well as monitoring and control methods.

Description

Hunting billbug adults measure .3-.4 inches in length and are black, charcoal gray, or brownish in color. The distinguishing characteristic for this species is a smooth, non-punctated Y-shaped area behind the head and parenthesis-like curved markings on the sides of the pronotum. They usually overwinter as adults or as partially mature larvae in the thatch, soil crevices, under mulch or leaf litter. The adults emerge from their overwintering sites as temperatures increase in the spring and will feed and mate. They are active at night and will feign death when disturbed. Damage by adults is most prominent in spring, but can also be seen in the fall. The adults will lay oblong, creamy white eggs from May into September. The eggs take 3-10 days to hatch. The larvae that hatch are white, legless and have a brown head capsule; they feed on the turfgrass stems and as they mature the crown, roots, and stolons. Larvae are most common from May to October. At full maturity, 3-5 weeks after egg hatch, the larvae measure .2-.4 inches in length. They will then pupate in the soil and 3-7 days later the adult hunting billbug emerges.

Damage

Hunting billbug adults and larvae feed on stolons, crowns, and new leaf buds. Due to feeding, the grass lacks sufficient roots to obtain water, nutrients, or stay anchored to the soil. Damage caused by hunting billbugs occurs on the surface as irregular, elongated, or rounded areas of brown and dying grass. Symptoms usually occur in early spring and summer. In bermudagrass hunting billbug damage is often misidentified as delayed spring green-up. During the summer months when bermudagrass is actively growing damage is often undetected. In zoysiagrass hunting billbug damaged turfgrass becomes chlorotic and tufts are easily lifted from the sod mat. When populations are high in fall damage is often misidentified as normal fall dormancy.

Control

To control adult populations apply insecticides in spring when adults emerge from their overwintering sites, but before they lay their eggs. Treat no later than 3 weeks after adults become active. The use of insecticides for adult control includes bifenthrin (Talstar, Menace etc), deltamethrin (Deltagard), lambda-cyhalothrin (Scimitar or Battle), or imidacloprid (Merit). The use of insecticides for larval control includes clothianidin (Arena) or thiamethoxam (Meridian). The use of insecticides for both adults and larval control include chlorantraniliprole (Acelepryn), clothianidin + bifenthrin (Aloft), or imidacloprid + bifenthrin (Allectus, Atera). Check the label for rates and application methods. Applications in the spring are preventative and should only be made on sites with a history of hunting billbugs. To control larval populations apply insecticides 6 weeks after the adults become active. At this point the larvae are in the root zone and are the most vulnerable. Be sure to water the insecticide in after application to insure insecticide movement through the thatch.