Knopper Gall

Firstly, many thanks for the response to yesterday's image.

I love that Blipfoto encourages me to look for the out of the ordinary, or interesting.  Today, I went out early for a walk, before the rain that was forecast arrived.  As I was walking passed this oak tree I noticed the unusual growth on this acorn.  I thought initially it might be a canker, but on researching there is a much more interesting reason.

Excerpt from an internet website:


The Acorn Gall wasp(Andricus quercuscalicis) causes Knopper Galls of Oak(Quercus) acorns. The wasp lays its egg on a developing acorn in early Summer. When the egg hatches the grub secretes chemicals which causes the acorn to develop into a gall. The grub pupates inside the gall and emerges in the following year. They have a two generation cycle and are usually found on trees in the same area as Oaks. The first generation adult wasps, all female, leave the galls in early spring and lay their eggs in oak buds. A sexual generation of male and female wasps hatch and mate, with the female returning to lay eggs on the English Oak.


Acknowledgement to www.donsgarden.co.uk