Friday, 2 May 2014
These galls on oak shoots are the result of an egg laid in the oak by a tiny gall wasp. The tree produces a soft, spongey 'oak apple', which provides food for the wasp grub at minimum cost to the tree.
The strange thing is that an egg from a different species of gall wasp will produce a different gall such as the marble gall, (which is hard and much smaller - like a marble), or the knopper gall (which is like a pine cone growing on the acorns).
Oak apples are present now on young oaks up near post 4 on the self-guided trail.