How to Manage Pests

Pests in Gardens and Landscapes

Poplar and willow borer—Cryptorhynchus lapathi

The poplar and willow borer is an atypical weevil occurring throughout most of the United States. Adults are 7.5 to 10 mm long, mostly black, and densely covered with dark bristles. The mostly pale larvae develop through six instars. All stages can occur year round and it can take up to three years to complete one generation.

Damage

Adult weevils chew bark and oviposit on current-year green shoots. Larvae chew mines 1 to 3 inches long beneath and in bark and in wood. Terminals die back and fine brown boring dust may be seen around entrances.

Solutions

Prune and dispose of infested and dying limbs or trees. Treatment may be warranted with a persistent insecticide to control adults when active and when infestations are heavy.

Poplar and willow borer adult
Poplar and willow borer adult

Poplar and willow borer
Poplar and willow borer adult (left) larva in wood (right)


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