Oak Wasp - The Gall!
Knopper Wasp indications in Sherborne
I wrote a couple of weeks ago about the “mast year” with plenty of nuts and fruit on the trees this year. Yesterday I was out picking a few acorns off the ground - planning to pop a few into posts to germinate in my green house over winter, when I noticed a significant number of deformed acorns. Below the tree I was collecting the acorns from, about half of them had a strange growth growing out of the acorn. Here’s some pics.
A bit of digging identified the culprit, I think. The “Knopper Gall Wasp” became established in the UK a few decades ago and is now apparently quite widespread. The wasp lays its eggs in developing acorns, which biologically responds by formation of these strange “galls” which appear to grow out of the acorn. So the wasp larva is a parasite of sorts, causing strange growths which I assume are optimised for the larva. I’m not sure if the initial laying of the egg causes the gall or whether the growing larva provide some sort off biological “kick” to the acorns so they produce these strange growths. Tell me if you know!
I had imagined that the gall wasp might have only affected a small proportion , but a 50% appearance amongst the acorns on the ground seems a lot. I assume that the emergent wasp comes out of the central hole at some point. Let me know if you can add useful facts to this.
Also let me know if you see examples of other galls on local trees and vegetation. It’s always worth picking up the odd acorn. Push it deep into the earth near where you find it, or bring to home and stick it in a pot somewhere safe and cool for winter. You can’t have too many oak saplings around and the Ancestor Oaks Project will be here for generations of Sherbornians, I hope. Remember when you plant an acorn you aren’t planning for next year - you are planting it for 500 years hence. What else can you do that will change the world in 500 years time - plant an acorn!
One other thing to report. Filming took place yesterday for the first video-podcast by “The_River_Girl” beside Waterloo Bridge. Debbie, the River Girl, is an environmental campaigner whom some of you have met on our earlier grip clearances. She concentrates her efforts on the Cotswold rivers, including the Coln and the Sherbrooke Brook. I’ll let you know the video link when it is published. For now here’s a snap of her examine a rock for wriggly things.
