Podosesia syringae

Lepidoptera: Sesiidae

Identification
• Larva is white, legless, soft-bodied, and up to 1¹/₂" long and lives in a tunnel in the trunk or branch.
• Adult is a dark brown, 1" long moth with narrow wings and resembles a paper wasp.

Damage
• The larvae tunnel deep into the trunk and branches of lilac and ash. (a)
• The moth emerges through a ¹/₄" diameter round hole. (b)
• Continual infestation causes branch dieback and the death of the tree or shrub.

Management
• Pruning out lilac trunks more than 1¹/₂" in diameter will eliminate borer attack.
• Avoid pruning newly planted ash trees or prune in late July to reduce borer egg-laying in the pruning wounds.
• Plant new ash trees properly and provide proper watering and mulching to help them adapt more quickly.
• Apply insecticide one week after peak pheromone trap catch or when vanhoutte spirea is in full to late bloom.