Cranberry Rootworm

Rhabdopterus picipes

Key Features

  • Crescent shaped channels in leaves
  • Injury in shade or heavily mulched soil
Crescent-like channels chewed by adult cranberry rootwom
Crescent- like channels on leaves by adult cranberry rootworm
Crescent- like channels made by adult cranberry rootworm


Adult beetles emerge from soil to cause distinctive channels on leaves. Damage tends to be in shady gardens with adequate moisture and an overabundance of mulch.

Crescent-like channels on viburnum made by adult cranberry rootworm


Adult beetles are small black beetles that emerge from pupae in spring to feed on a wide variety of host plants. Adults hide in moist mulch during the day and feed night. Adults lay eggs that turn in to larvae that feed on the roots of a wide variety of grasses, and other plants including blueberry, and cranberry.

Management Recommendations

Remove excessive mulch, moisture, and shade that provides shelter for adult beetles. This should get rid of the problem. In the event that it is not possible to change the habitat, applications of a foliar insecticide at the first sign of feeding would kill beetles. Spinosad is preferred over other products that can also kill beneficial insects.

Effective Pesticides

Active Ingredients include: Bifenthrin, Carbaryl, Lambda- cyhalothrin, Permethrin, Spinosad

landscape report
Purdue Landscape Report
Plant & Pest Diagnostic Laboratory