Hunting billbug

What is hunting billbug?

The hunting billbug is a weevil that feeds on warm-season turfgrasses. UGA calls it an important turf pest in Georgia, with especially serious damage on zoysia, and Oklahoma State lists zoysia, hybrid bermudagrass, bahiagrass, centipedegrass and St. Augustinegrass as hosts. It is mainly a southern pest; in Pennsylvania's cool-season lawns, the related bluegrass billbug is the one to watch.

Adults chew small holes in grass stems and lay eggs inside. Young larvae feed inside the stem, then move to the outside of stems and stolons and finally to the roots. The turf shows yellowish-brown patches that do not respond to watering, and dead patches contain hollow stems packed with frass. In some zoysia cultivars, last year's feeding shows up as slow green-up the next spring.

Damage is often misdiagnosed as white grubs, drought, nutrient problems, spring dead spot or winterkill. UGA also warns that moving infested bermudagrass or zoysia sod can spread billbugs to new sites.

Signs and damage

• Yellowish-brown or dead patches mixed in with green turf that do not improve with regular watering.
• Zoysia that is slow to green up out of winter dormancy, from feeding the year before.
• Hollow stems packed with sawdust-like frass in dead patches.
• Stems that break away easily when tugged.
• Sod that falls apart when cut.
• Snouted beetles on sidewalks and driveways early in the morning.

Hunting billbug identification: what to look for

• Adult: About 0.3 to 0.4 inch (roughly 3/8 inch), black, charcoal gray or brown, with a long snout tipped with small jaws. Smooth Y-shaped area behind the head and parenthesis-shaped marks on the sides of the thorax.
• Larva: White, legless grub with a brown head; five stages from about 1.3 mm to 6 to 10 mm at maturity, reached in about 3 to 5 weeks.
• Eggs: Creamy white and bean-shaped, laid singly in feeding holes chewed into grass stems; they hatch in 3 to 10 days depending on temperature.
• Damage: Patches of dry, yellow or dead grass within green turf; hollow, frass-filled stems; slow spring green-up in zoysia.
• Timing: Eggs from May through September and larvae from May to October in North Carolina; two overlapping generations there, more farther south.

Life cycle

Adults spend the winter in thatch, soil cracks, mulch or leaf litter, and some larvae overwinter too. Adults come out on warm spring days, feed and mate. Females lay eggs singly in stems from May through September (North Carolina). Eggs hatch in 3 to 10 days. Larvae feed inside stems, then on crowns, stolons and roots, maturing in about 3 to 5 weeks, then pupate in the soil; adults emerge 3 to 7 days later. Two overlapping generations a year have been reported in North Carolina and six in Florida, and in southern Georgia all stages occur year-round (NC State, UGA).

When to look: Look for adults at night or on pavement early in the morning in spring. Watch for patchy damage and slow green-up in zoysia and bermudagrass lawns from spring through fall.

Hunting billbug look-alikes

A few things get mixed up with it:

• Bluegrass billbug (Sphenophorus parvulus): A close relative that prefers Kentucky bluegrass, perennial ryegrass and fescues in cool-season lawns, with one generation a year.
• Annual bluegrass weevil (Listronotus maculicollis): About one-third the size, with a shorter, stouter snout and antennae near the tip; it attacks short-mown golf turf.
• White grubs (Scarab beetle larvae (several species)): C-shaped with six legs. Billbug larvae are legless and leave frass-packed hollow stems.

How to control hunting billbug

Cultural control

• Keep the turf watered and fed adequately so it can tolerate feeding (UGA).
• Some grasses resist billbugs: UGA notes reported resistance in 'Zeon' zoysia and in endophyte-infected ryegrass and fescues.
• Avoid moving infested sod; bermudagrass and zoysia sod with larvae can carry billbugs to new sites (UGA).
• Keep records of where damage showed up before, and use the tug test on suspect patches.
• Monitor adults with pitfall traps (a cup or slit pipe set flush with the soil) checked weekly, or by searching with a flashlight at night (UGA).

Biological control

• Insect-parasitic nematodes (Steinernema carpocapsae, S. feltiae and Heterorhabditis bacteriophora) have been reported to control larvae, but results depend on nematode numbers and soil moisture and temperature (UGA).
• Natural enemies include an egg parasite (Anaphes calendrae), a larval parasite (Zavipio belfragei, whose impact is unknown), spiders, ground and rove beetles, ants, toads and birds (UGA).

Chemical control

Spring treatments aimed at adults are preventive and belong only on sites with a history of hunting billbug; NC State says to apply when adults become active and before egg laying, no later than 3 weeks after adults appear, and UGA times them for late winter and early spring. UGA and NC State name the pyrethroid bifenthrin for adults. Treatments aimed at larvae go on about 6 weeks after adults become active, in late spring to early summer, and are watered in; the neonicotinoids imidacloprid, clothianidin and thiamethoxam and the diamides chlorantraniliprole and cyantraniliprole are named. In southern areas with year-round activity, timing varies. Use only products labeled for this use; the label is the law.

Use only products labeled for this pest and this site; the label is the law. For trees, work with an ISA Certified Arborist. If you hire someone to apply pesticides, make sure they hold your state’s pesticide applicator license; the rules for each state are in our pesticide applicator license guide.

Prevention

• Plant resistant grasses where billbugs are a known problem.
• Inspect sod for billbug larvae and frass before installing it.
• Keep turf healthy so it can outgrow light feeding.

When to call a pro

Call a licensed pesticide applicator (see our pesticide applicator license guide) if a zoysia or bermudagrass lawn has repeat billbug damage or slow spring green-up with frass-filled stems.

Related guides: Weed identification guide · All pests and diseases

Questions about hunting billbug

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