Lilac-Ash Borer

    Lilac-Ash Borer

    Podosesia syringae 

    lilac-ash borer

    Lilac-ash borer (James Solomon, USDA Forest Service, Bugwood.org)

    lilac-ash borer larva

    Lilac-ash borer larva (James Solomon, USDA Forest Service, Bugwood.org)

    lilac-ash borer damage

    Dieback caused by lilac-ash borer (James Solomon, USDA Forest Service, Bugwood.org)

    Pest Description

    • adults: 1 – 1 1/2 inches; black with yellow markings
    • look like paper wasps
    • larvae: up to 1 inch; pinkish-white with a brown head capsule

    Host Plants, Diet & Damage

    • ash; privet; lilac
    • major pest of smaller ash trees in Utah
    • larvae feed on cambium tissue and sapwood
    • primarily found in the trunk and larger branches
    • limb and canopy dieback are common
    • leave irregularly round exit holes
    • pupal skins extrude from exit holes (eventually fall out)

    Biology, Life Cycle & Damaging Life Stage

    • overwinter as larvae in chambers in the trunk
    • adults are active late-April through late-July (northern Utah)
    • eggs laid on bark
    • larvae bore directly into cambium/sapwood layers to feed
    • one generation per year
    • larvae are the damaging stage

    IPM Recommendations

    • Monitor using delta traps and a clearwing moth pheromone lure starting in April.
    • Hang monitors from branches at about shoulder height.
    • Keep trees healthy and stress free.
    • Do not plant ash (Fraxinus spp.) trees.
    • Use a horticultural tree wrap to protect from winter sun.
    • Use renewal pruning to remove older, more susceptible branches.
    • Prior to moth flight, apply an insecticide (anthranilic diamide; pyrethroid) to stem and main scaffold branches.
    • Systemic neonicitinoids are not effective against this insect.

    For more information, see our Lilac-Ash Borer fact sheet.