Turfgrass-White grub

Includes Popillia japonica and Aphodius majale

Pest description and crop damage White grubs are the larvae of a number of scarab beetle species. Destructive turfgrass pests found in the Pacific Northwest in the scarab beetle family include the invasive Japanese beetle (Popillia japonica) and European chafer (Aphodius majale). May and 10-lined June beetles (Polyphylla spp.) are also found in the Pacific Northwest but are rarely detrimental to turfgrass. The adult Japanese beetle is 0.5 inch in length with iridescent, copper-colored wing covers and a green thorax and head. The adult European chafer is 0.5 inch in length (much larger than billbug larvae) with a light-brown or tan colored head, thorax, abdomen and wing covers. The insect's eyes are dark-brown to black. Japanese beetle and European chafer larvae or grubs feed on turfgrass roots. These grubs have robust, cream-color bodies, dark-brown heads and six legs and reach of length of 1 inch in the fall. Mammals (skunks, racoons and birds) will uproot large sections of turf in the fall when feeding on these grubs. Grubs that make it through the fall and winter months will produce damage in the following spring and summer months. Damage at this time appears as patches of turf that are not anchored to the soil and are prone to drought and heat stress despite regular irrigation. Populations of these invasive insects are most prevalent in the Seattle/Tacoma area, with small satellite populations observed in the Portland area.

Biology and life cycle Adult Japanese beetle and European chafer are found flying in June and July. The mature or late instar larval populations cause the most damage from October to the subsequent May.

Scouting and thresholds Scouting should be initiated in the fall months (August and September), before larvae reach maturity or the third instar. At this time damage will increase and preventative, low-impact insecticide will be less effective. Mammal predation will begin in the fall and continue in the spring. Insects surviving to the spring will produce visible damage in the late spring and summer months. Symptoms will include heat and drought stress, and a compromised root system. Action thresholds are between 5 to 10 larvae for sq ft in well-maintained turfgrass. Scout in the top 2 inches of the soil using a shovel.

Management-biological control

  • beneficial nematodes-Read label carefully for application procedures, timing and appropriate soil temperatures for best efficacy.

Management-chemical control: HOME USE

Spray when grubs are active near the soil surface. Irrigate the treated area immediately after application with 0.5 to 1 inch water to wash insecticide into underlying soil. Do not permit children or pets on the treated turfgrass until it has been watered to wash the insecticide into the turf and the grass is completely dry. Most insecticides are toxic to bees exposed to direct treatment or to residues on blooming weeds/ flowers in lawns: mow and remove clippings prior to applying insecticides.

  • bifenthrin (often as a mix with other active ingredients)
  • carbaryl
  • chlorantraniliprole
  • imidacloprid
  • permethrin
  • spinosad (as a mix with insecticidal soap)

Management-chemical control: COMMERCIAL USE

Spray when grubs are in the early instar period (August and September). Irrigate the treated area immediately after application with 0.5 to 1 inch water to wash insecticide into underlying soil. Do not permit children or pets on the treated turfgrass until it has been watered to wash the insecticide into the turf and the grass is completely dry. Most insecticides are toxic to bees exposed to direct treatment or to residues on blooming weeds/ flowers in lawns: mow and remove clippings prior to applying insecticides.

  • acephate (Orthene Turf Tree & Orn. WSP)
  • azadiractin (Nemix 4.5 IGR)-OMRI-listed for organic use.
  • bifenthrin (Talstar, Capture, Brigade)
  • carbaryl (Sevin Brand RP4 Carbaryl, Lebanon Sevin 7G Granular Insect Control, Sevin SL Carbaryl Insecticide)-For larvae.
  • chlorantraniliprole (Acelepryn Insecticide, Acelepryn G Insecticide)-For larvae.
  • clothianidin (Arena 0.25G Insecticide, Arena, 50 WG Insecticide, Arena 50 WDG Insecticide)-Apply as soon as overwintering adults are seen in the spring. Note: Neonicotinoid pesticides have been banned from use on public properties in some towns and counties (check with local authorities).
  • dinotefuran (Zylam)-Provides only suppression of white grub larvae. Must apply prior or during egg hatch for control. Note: Neonicotinoid pesticides have been banned from use on public properties in some towns and counties (check with local authorities).
  • imidacloprid (Fortify Season Long Grub Control, Adonis 2F Insect Conc., AmTide Imidacloprid, Avatar PLX Insecticide, Lesco Bandit 0.5G Granular Insecticide, Lesco Bandit 2F Insecticide, Lesco Bandit 75 WSP Insecticide, Malice 0.5G, Malice 2F Insecticide, Malice 75WSP, Mallet 0.5G Insecticide, Mallet 2F Insecticide, Mallet 2F T&O Insecticide Mallet 75 WSP Insecticide, Mallet 7.1% PF Insecticide, Merit 0.5G Insecticide, Merit 2F Insecticide, Merit 75WP Insecticide, Merti 75WSP Insecticide, Midash 2SC T&O, Prokoz Zenith 0.5G Insecticide, Prokoz Zenith 2F Insecticide, Quali-Pro Imidacloprid 0.5G, Quali-Pro Imidacloprid2F T&O, Quali-Pro Imidacloprid 75 WSB Insecticide in WSP)-For larvae. Note: Neonicotinoid pesticides have been banned from use on public properties in some towns and counties (check with local authorities).
  • spinosad A & D (Conserve SC Turf & Ornamental Insect Control)
  • thiamethoxam (Meridian 0.33G Insecticide, Meridian 25WG Insecticide, Flagship 25WG Insecticide)-Note: Neonicotinoid pesticides have been banned from use on public properties in some towns and counties (check with local authorities).
  • trichlorfon (Dylox 6.2 Granular, Dylox 420 SL Turf & Ornamental)-For larvae.