Club-like swollen shoots and twigs with ring-shaped scars from feeding.
Affected tree species
In spring, the adult wasps damage young shoots and twigs in order to feed from the sap; the minute wounds either girdle the whole shoot or cover only parts of it leading to callus production. Consequences are secondary fungal infections, wood rot and increased danger of breakage. The damage seems to be common in plantations. Further information and fotos:Waldwissen_net .
Curative measures Hardly any possible; at most exposure of traps covered by glue, when the imagines are active in spring