How to Manage Pests

Pests in Gardens and Landscapes

Seasonal development and life cycle—American plum borer

Adult moths emerge from cocoons in April and May. Females lay eggs near pruning wounds, in scaffold crotches of young trees near graft unions, or on crown galls. Young larvae hatch and bore into the tree leaving reddish orange frass. Their frass, webbing, and gum pockets indicate their presence. They overwinter as mature larvae in a cocoon within the tree. There are three to four generations each year.

Plum borer larva
Plum borer larva

Plum borer adult
Plum borer adult

Damage to scaffolds
Damage to scaffolds

Frass from larvae
Frass from larvae

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