How to Manage Pests

UC Pest Management Guidelines

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Turfgrass

Billbugs

Scientific Names:
Phoenix billbug: Sphenophorus phoeniciensis
Hunting billbug: Sphenophorus venatus vestitus

(Reviewed 6/03, updated 6/03)

In this Guideline:

Description of the pests
Susceptible species
Damage
Management

DESCRIPTION OF THE PESTS
The Phoenix and hunting billbug adults are dark brown and light brown, respectively. Both are 0.33 inch (8.38 mm) long weevils (snout beetles) with a long, downward-pointing snout and elbowed, clubbed antennae. The Phoenix billbug is more common in California than the hunting billbug. The hunting billbug can be identified by a Y-shaped marking on the thorax with separate, inward-facing marks that resemble parentheses on either side of the Y. These two marks in the Phoenix billbug combine to form an M. Adults are often seen walking on paved areas, but are difficult to find on golf courses unless a drench test is used. Eggs are inserted into the turfgrass stems. They hatch about 6 to 8 weeks after adults first appear. Larvae are creamy white, legless, and somewhat hunch-backed C-shaped grubs with a brown head. The lack of legs distinguishes billbug grubs from white grubs.

SUSCEPTIBLE SPECIES
All species of turfgrass can be damaged. However, zoysiagrass is preferred by hunting billbugs while phoenix billbugs prefer bermudagrass.

DAMAGE
Billbug larvae first feed on the inside of the turfgrass stem and crown, then move into the soil where they feed on roots. Fine, whitish, sawdustlike larval excrement (frass) can be observed on the soil surface. Billbug larvae feed higher up on the roots than white grubs, so billbug-damaged turf is easier to pull from the soil than that damaged by white grubs because it breaks at the crown. Billbugs may feed on roots to a depth of 3 inches; however, unlike turf damaged by white grubs damaged turf cannot be rolled back like a carpet and the soil does not feel spongy underfoot. Turfgrass planted on fumigated soil is especially susceptible to damage because of the loss of natural enemies. Drought-stressed turfgrass may be severely impacted.

MANAGEMENT
If you suspect a billbug infestation, look for piles of fine frass at the base of turfgrass plants. In areas where frass or damage is evident, dig up the turfgrass to look for grubs. (For more information on monitoring, see GENERAL INFORMATION.) Treat when one or more grubs are found per square foot of turfgrass. Commercially available nematodes, Steinernema carpocapsae or Heterorhabditis bacteriophora, often control billbug larvae, especially in sod farms or other locations where the soil has been fumigated. Apply nematodes to moist turf and irrigate following application of either nematodes or chemical insecticides to move the material into the zone of larval feeding activity.

Note: many of these products are available for licensed applications only and cannot be used by home gardeners.

Common name

(trade name) Amount/1000 sq ft**

Many of these products are available for use by licensed applicators only and cannot be used by home gardeners.

A. CHLORPYRIFOS

(Dursban Pro) 1.5-3 fl oz

(Dursban) 50W WSP* 0.75-1.5 oz

COMMENTS: For use in turfgrass production and on golf coursesonly. This product is highly toxic to birds and aquatic invertebrates. State and federal agencies have determined that waterways have been impaired by the use of this material. Do not apply in such a manner that it will get into storm water drains.

B. DELTAMETHRIN

(DeltaGard T & O) 5SC 0.6-0.9 fl oz

COMMENTS: To control adults. Not for use on sod farms or in commercial seed production.

C. IMIDACLOPRID

(Merit) 75 WP 3-4 teaspoons (0.15-0.19 oz)

(Merit) 75 WSP 0.15-0.19 oz (1 packet/8,250-11,000 sq ft)

COMMENTS: Maximum of 1 application/year. Applications cannot exceed 8.6 oz/acre/year (0.19 oz/1000 sq ft). Optimum control will be achieved when applications are made before egg hatch of the target pests followed by sufficient irrigation or rainfall. Applications should not be made when turfgrass areas are waterlogged or soil is saturated with water.

D. STEINERNEMA CARPOCAPSAE 25 million

...OR...

HETERORHABDITIS BACTERIOPHORA 25 million

COMMENTS: Most effective larval treatment and the preferred choice on soil that has been fumigated to reintroduce these parasites into the soil. Store nematodes properly before use as directed. Apply to warm, moist, but not soggy soil. Several irrigations may be needed during 2 weeks after application to keep soil moist. Apply during the coolest time of day in hot areas.

** Apply sprays in 25 gal water/1000 sq ft

* Permit required from county agricultural commissioner for purchase or use.

PUBLICATION

UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
Insects and Mites
H. S. Costa, Entomology, UC Riverside
R. S. Cowles, Entomology, Connecticut Agricultural Experiment Station, Windsor, CT
M. A. Harivandi, UC Cooperative Extension, Alameda Co.
J. Hartin, UC Cooperative Extension, San Bernardino Co.
H. K. Kaya, Nematology, UC Davis
Acknowledgment for contributions to the insect and mite section:
K. Kido, Entomology, UC Riverside

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