WSU Extension


Bacterial twig blight 
Marssonina leaf & twig spot 
Twig blight (Venturia) 
Poplar-and-willow borer 
Satin moth 
Spiny elm caterpillar 

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Caption: Poplar-and-willow borer adult
Photo by: A.L. Antonelli
Willow : Poplar-and-willow borer
(revision date: 6/29/2015)

The adult poplar-and-willow borer is a black and white weevil (a flightless beetle) about 3/8" long. The larvae are white and legless and mine beneath the bark and in trunk and branches. Feeding larvae expel large quantities of frass (sawdust-like excrement) through holes they keep open in the bark. The feeding larvae may girdle branches, resulting in leaf wilt and eventual branch death. When mature, larvae are approximately 1/4" long. Severe infestations cause swollen, lumpy bark, bark scars with exposed wood, and sometimes considerable production of shoots from old wood. Willows are preferred, but the borer will also attack poplar species.
Management Options

Non-Chemical Management
  • Remove seriously infested trees.
Select non-chemical management options as your first choice!

Chemical Management

None recommended.


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Caption: Poplar-and-willow borer adult
Photo by: A.L. Antonelli
Caption: Poplar-and-willow borer damage
Photo by: S.J. Collman