Includes
Ten-lined June beetle (Polyphylla decemlineata)
Rain beetle (Plecoma spp.)
Aphodius spp.
Pest description and crop damage Small to large C-shaped, white scarab beetle larva with six legs and a brown head. Grubs feed on roots, often killing young trees. Many follow the soil moisture and may appear absent in summer.
Management-biological control
Some growers have observed partial control from parasitic nematodes, but results are poorly replicated.
Management-chemical control
To date, chemical control on established large grub populations has not been effective.
- bifenthrin (OnyxPro, Sniper and others) (Group 3)-Restricted use pesticide.
- carbaryl (Sevin and others) (Group 1A)
- cyantraniliprole (Mainspring GNL) (Group 28)
- imidacloprid (Montana, Nuprid 2F and others) (Group 4A)
- thiamethoxam (Flagship 25 WG) (Group 4A)
Douglas-fir