How to Manage Pests

Pests in Gardens and Landscapes

Seasonal development and life cycle—Weevils

Peak adult weevil populations occur in summer and early fall, and some may overwinter.  Female weevils may feed for an extended period before laying eggs, and many species produce viable eggs without mating. Eggs are laid in soil near the base of plants about 4 to 6 weeks after adults have emerged. A single female may lay as many as 500 eggs. Eggs hatch into legless, white grubs that feed on roots. The larvae develop in soil through 6 instars over a period of 2 to 8 months.  They are whitish grubs with a brown head and commonly have a C-shaped posture. 

Black vine weevil overwinters primarily as a late-instar larva.  A few individuals of this and other species can overwinter as adults.  Weevils overwintering as late instars form pupae in spring.  Adult weevils emerge in late spring or summer and feed on the foliage of host plants at night. Adults do not fly, but may crawl into new plantings from nearby native plants, ornamentals, blackberries, or second-year strawberries.

Root weevil pupa (left) and larva (right)
Root weevil pupa (left) and larva (right)
Adult black vine weevil on euonymus leaf

Statewide IPM Program, Agriculture and Natural Resources, University of California
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