You may think this Oak Apple is in the wrong gallery 'Bees and Wanna'bees' but this fascinating
structure is the result of the work of a Gall Wasp (Superfamily Cynipoidea; Order Hymenoptera).
These insects lay their eggs in spring on young leaves or stems. When the eggs hatch, secretions
from the wasp larva subvert the normal growth of the leaf and cause it to form the gall, a safe
house in which the grub can develop. A hole in the Gall usually indicates the adult wasp has emerged.
There are over a 1000 species of Gall Wasps and they produce Galls in a wide variety of shapes.