A gall on Sweet Chestnut (Castanea sativa) caused by a gall wasp of the family Cynipidae. The species is of Asian origin and is invasive in Europe and North America.
It's great to see things like this, Martin. Would it be possible for you to add a little text to describe it, though...that would seem to be the role of an expert in a field, to help the rest of us learn! Is it a gall midge or what?
My Flickr photos...
I added some information to the Description.
Thanks for that...so much better to have that bit of information!
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