Cynipid Gall Wasps

    Cynipid Gall Wasps


    cynipid gall wasps

    Galls formed by cynipid gall wasps (Gyorgy Csoka, Hungary Forest Research Institute,

    marble galls

    Marble galls (Milan Zubrik, Forest Research Institute - Slovakia,

    cynipid gall wasp galls

    Cynipid gall wasp galls (William M. Ciesla, Forest Health Management International,

    Pest Description

    • adults: very tiny and seldom seen
    • larvae: grub-like; found within galls
    • pest noticed by the presence of galls
    • each species creates a unique gall

    Host Plants, Diet & Damage

    • most common on roses and oaks
    • galls can occur on acorns, branches, buds, flowers, leaves, roots and twigs
    • larval feeding causes round, spiny, single/multiple or other types of galls
    • galls do not typically affect the overall health of the tree
    • excessive galling of branches and twigs can cause plant stunting or dieback

    Biology, Life Cycle & Damaging Life Stage

    • overwinter as larvae in the gall
    • pupate within the gall or in the soil in spring
    • emerge in April and May, coincident with budbreak
    • eggs laid on emerging plant tissue or on/in swollen buds
    • larval feeding produces galls
    • most have one generation per year
    • larvae are the damaging stage

    IPM Recommendations

    • Galls do not affect the overall health of the tree; tolerate pest.
    • Rake and remove fallen leaves in the fall.
    • Remove galled plant parts and destroy.
    • Management with insecticides can be difficult and spotty.
    • Apply an insecticide (carbamate; pyrethroid) at or just prior to budbreak to prevent egg laying to reduce gall formation (may not prevent all new gall formation).