Oak Tree Knopper Gall Drawing
This drawing was made on site at Crunch 09 – Arts Festival at Hay on Wye 15th November 2009. The drawing was made beneath the oak tree in the garden of the globe at Hay. Found fallen oak tree knopper galls were collected from underneath the oak tree and laid to form this drawing which measured c. 15 x 20ft. Oak knopper galls are caused by the tiny gall wasp Andricus quercuscalicis, which lays its eggs in the acorn. Chemicals secreted by the wasp grub alters the normal cell division process and causes the oak to produce gall tissues that enclose the grubs providing both protection and food. The grubs feed on a nutritious layer of cells inside the galls.