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The Hunt for the Knopper Gall.

I’m really excited about these at the moment, any oak tree I come across I'm intently examining it.

They come in many different types and shapes and are entirely down to the egg laying abilities of the gall wasp. I have a love of shapes in natural forms and am totally awestruck by these mega shape shifters.

Knopper galls are specifically the ones which change the shape of the acorn. The gall wasp lays its eggs in the oak flowers in spring and as the acorn grows the larvae hijacks it sucking all its nutrients and morphing the shape into something completely different. Exactly how they do it is still seen as a bit of a mystery.

Galls come in all different styles of shapes determined by the species of gall wasp. Some are smooth or roughly spherical in shape, others are like extruded chewing gum frozen in mid stretch, and some (I get excited about this) appear to show a recognizable geometric form.

The knopper gall is the most common one that I have found. They look like exploded walnuts and if you compare a few you can recognize a definite pattern and similarity in how they form. It's understood that the larvae hatching inside the oak flower adapts the chemical signals at the developmental stage to create these structures of such diversity.

Other galls will appear on undersides of leaf instead of hijacking the flower.

What is also interesting is that the next generation of wasps hatched from these will create different galls in another tree species. They sort of alternate years, sometimes all being male or only female wasps that generate different type of galls.

As well as the Knopper I also found several Marble galls which I really like, the hardened sphere of a what seems like a nut. With a small hole where the wasp has left.

Galls come in all types and I spent a bit of time trying to find as many types as possible. You can see the whole collection here.

Marble galls have been valued through history. It was crushed galls mixed with water that created the first indelible ink used in the Middle Ages and is still present on legal and historical documents in museum archives.

Now that's not bad for a humble wasp!

Lisa Lillywhite - The Smart Happy Project, bringing numbers and nature together - www.thesmarthappyproject.com


Want to hunt for your own galls? Check out our spotting sheet & get looking!