Podosesia syringae

Distinguished from emerald ash borer (Agrilus planipennis) by round or oval exit holes rather than the characteristic D-shaped exit holes of the beetle. Sawdust-like frass accumulation on bark and ground is a key sign, contrasting with the galleries of emerald ash borer. Papery pupal cases protruding from bark distinguish it from other borers that do not leave such structures. Adults emerge in spring and early summer, unlike the related banded ash clearwing (Podosesia aureocincta) which emerges in autumn.

Associated with ash trees (Fraxinus spp.) and lilac (Syringa spp.), particularly in urban and suburban landscapes. Trees in stressful conditions—such as those planted along streets, in parking lot islands, or with limited root space—are more susceptible to infestation.

Throughout Canada and the United States. Specific records include Alberta, Manitoba, and Saskatchewan in Canada.

Adults emerge and are active in spring and early summer. Larval development continues through autumn, spring, and summer. The USA National Phenology Network provides predictive forecast maps for emergence timing based on heat accumulation models.

Larvae feed on the nutritious tissue beneath the bark of ash and lilac trees. Adults do not feed.

• Fraxinus - larval hostash trees
• Syringa - larval hostlilac

Females deposit eggs on bark. Eggs hatch in days. Larvae tunnel beneath bark and feed, growing through autumn, spring, and summer. Mature larvae pupate, and adults emerge through round or oval exit holes in the bark, leaving papery pupal cases. One generation per year is typical.

Adult females release pheromones to attract males. Adults are diurnal and wasp-mimicking in flight. Larvae bore beneath bark and expel frass from galleries.

As a wood-boring insect, larvae contribute to the degradation of living woody tissue in host trees. Their activity can stress or kill trees over time, potentially creating habitat for other organisms in dead or dying wood.

Significant pest of ornamental ash and lilac in urban and suburban landscapes. Damage from larval tunneling causes canopy thinning, branch death, yellowing leaves, and water sprout formation. Managed through cultural practices that reduce tree stress and by certified arborists. Included in USA National Phenology Network Pheno Forecast maps to aid integrated pest management professionals in timing control measures.

• Podosesia aureocinctaAlso a clearwing borer of ash, but adults emerge in autumn rather than spring and early summer; has yellow band on abdomen
• Agrilus planipennisEmerald ash borer is a beetle that kills trees rapidly and leaves D-shaped exit holes, unlike the round/oval holes and papery pupal cases of Podosesia syringae

• clearwing moth
• wood borer
• urban pest
• forest pest
• wasp mimic

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• National Phenology Network Aids Pest Management With Insect Forecast Maps
• The lesser ash threat? Banded ash clearwing borer, Podosesia aureocincta — Bug of the Week
• Biology of an Ash Borer, Podosesia syringae,1 in Green Ash in Mississippi