Pest: Giant European Hornet (Vespa crabro germana Christ)
Primarily attacks Lilac (Syringa) and Birch (Betula) but also found on Willow (Salix), Mountainash (Sorbus), Poplar (Populus), and Rhododendron. (Johnson and Lyon).
These are rather large wasps that resemble cicada killer wasps. During August and September the adults can be seen using their mandibles to peel bark from the small stems of host plants, which leads to the girdling and death of those stems. This bark is then used to make nests. In the late summer and early fall they may also attack nearly ripened apples that are still on the tree and can cause great losses at harvest time, especially in smaller orchards.
If found on fruit trees, a fruit tree management guide needs to be consulted for currently recommended insecticides. On landscape and nursery plants, one must consult a similar guide, for those plants, to obtain current recommendations for preventative sprays.
Written by: Robert Childs