August 23rd – I don’t know what it is in the season, but the acorns this year are prolific and absolutely huge. With the dry summer I’d have expected the opposite, but they are absolutely huge.
The fecundity of the crop is, however, being affected by the large amount of knopper galls, that from from acorns attacked by the knopper wasp. Also a peculiar seasonal phenomenon, they are very,. very red this year, whereas it’s usually just tinges of colour.
August 13th – At Hortonwood in Telford, I found a small wayside oak sapling, which was growing round, large acorns. they were generally healthy and surprisingly large, with only a handful affected by knapper galls – and where they were, the actual effect of the acorn remained small.
The ants were clearly interested in the acorns, but I have no idea why, and I’m wondering if the low gall-count and manner of development is maybe signifying and evolved defence to these parasites.
Certainly is fascinating. Going to be a good crop of acorns this year I think, and a bumper hedgerow harvest generally from what I can see so far.
July 25th – These oak knopper galls actually took me by surprise a couple of days ago, but the photos I took weren’t great, so I revisited the saplings they’re growing on today.
I spotted them on a tree near Victoria Park in Darlaston and I don’t think there’s a single normally formed acorn on that tree at all, and yet several adjacent ones have no knoppers at all.
These mutations of normal acorns are of course caused by a tiny wasp that lays eggs in the acorn buds earlier in the year. A secretion the eggs are coated in causes the acorn bud to mutate and grow in a distorted form, forming a gall, with the wasp egg at the centre.
The larva hatches, and eats it’s way out of the gall, which provides it enough nourishment to grow to maturity.
Insect galls like this don’t hurt the tree, but of course, do affect it’s fecundity.
Isn’t nature amazing?