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How to Manage Pests

UC Pest Management Guidelines


Adult Phoenix or Phoenician billbug.

Turfgrass

Billbugs

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

(Reviewed 9/09, updated 9/09)

In this Guideline:


DESCRIPTION OF THE PESTS

The Phoenix and hunting billbug adults are dark brown and light brown, respectively. Both are 0.33 inch 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. Adults may be found all year round.

SUSCEPTIBLE SPECIES

Although all species of turfgrass can be attacked, serious damage is seen primarily on bermudagrass and zoysiagrass. 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

Where possible choose resistant varieties of bermudagrass and zoysiagrass or other less susceptible turf species. Perennial ryegrasses with endophyte fungal enhancement are resistant to billbug attack and can be used to overseed in fall. Good irrigation, fertilizing, and mowing practices may allow turf to tolerate low levels of billbugs.

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 MONITORING AND TREATING INSECTS AND MITES. 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.

With overlapping generations and a long season in California, billbugs are difficult to control with insecticides. Preventive grub materials (imidacloprid, thiamethoxam) are quite effective, but must be applied before eggs are laid and damage detected. They kill the next generation of young larvae. Curative treatment of billbug grubs with currently available insecticides is difficult.

Common name Amount/1000 sq ft** Ag Use
R.E.I.+
NonAg Use
R.E.I.+
(trade name)   (hours) (hours)

  Calculate impact of pesticide on air quality
The following materials are listed in approximate order of usefulness in an IPM program, taking into account efficacy and impact on natural enemies and the environment. Not all registered materials are listed. Not all registered pesticides are listed. Always read label of product being used.
 
A. IMIDACLOPRID
  (Merit) 75 WP 3–4 teaspoons (0.1480–0.19 oz) 12 until dry
  (Merit) 75 WSP 0.15–0.19 oz (1 packet/8,250–11,000 sq ft) 12 until dry
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Optimum control will be achieved when applications are made before egg hatch followed by sufficient irrigation or rainfall. Maximum of 1 application/year. Do not exceed 8.6 oz/acre/year (0.19 oz/1000 sq ft). Applications should not be made when turfgrass areas are waterlogged or soil is saturated with water.
 
B. THIAMETHOXAM
  (Meridian) Label rates 12 until dry
  MODE OF ACTION GROUP NUMBER1: 4A
  COMMENTS: Optimum control will be achieved when applications are made before egg hatch followed by sufficient irrigation or rainfall.
 
C. STEINERNEMA CARPOCAPSAE 25 million NA NA
  . . . or . . .
  HETERORHABDITIS BACTERIOPHORA 25 million NA NA
  COMMENTS: Effective larval treatment if applied while larvae are young in summer. Apply to moist but not soggy soil. Several irrigations may be needed.
 
D. CARBARYL*
  (Sevin) 80WSP 3.67 oz 12 until dry
  MODE OF ACTION GROUP NUMBER1: 1A
  COMMENTS: For treatment of grubs later in the season.
 
E. DELTAMETHRIN
  (DeltaGard T & O) 5SC 0.6-0.9 fl oz until dry
  MODE OF ACTION GROUP NUMBER1: 3
  COMMENTS: To control adults. Not for use on sod farms or in commercial seed production. May cause water quality issues.
 
** Apply sprays in 25 gal water/1000 sq ft.
* Permit required from county agricultural commissioner for purchase or use.
1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent the development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Agricultural use applies to sod farms and commercial seed production.
NA Not applicable.
Indicates use is not listed on label.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Turfgrass
UC ANR Publication 3365-T
Insects and Mites
M. L. Flint, UC IPM Program, UC Davis
M. A. Harivandi, UC Cooperative Extension, Alameda County
H. K. Kaya, Nematology, UC Davis
Acknowledgment for contributions to Insect and Mites:
J. Hartin, UC Cooperative Extension, San Bernardino County
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT
K. Kido, Entomology, UC Riverside
H. S. Costa, Entomology, UC Riverside
D. D. Giraud, UC Cooperative Extension, Humboldt/Del Norte counties

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