As I've wandered the trails around The Lodge recently, I've noticed something strange. Where there should be smooth, shiny, ripening acorns dangling from the oak twigs, there are distorted, crinkly growths which - to my eyes, anyway - look a bit like Ferrero Rocher chocolates...
It turns out that this is the work of a small wasp which goes by the snappy name of Andricus quercuscalicis. The weird growths themselves are known as 'knopper galls' - the word knopper being derived from a word for a knob, stud, tassel or hat.
The 'gall' is the growing acorn's response to the wasp grubs developing inside after eggs were laid there earlier in the year. In a similar way, you might have seen the robin's pincushion gall before - it's a common sight on wild rose bushes, with a tangled mass growing from the stem eventually turning red.
At The Lodge, at least, there are not many acorns to be found this autumn. The galls are turning brown and falling off the trees, and the newly-hatched wasps making their escape.
Jays are famous for their love of acorns, able to store away as many as 5,000 for a rainy (or cold) day. What will they do here this year?
As members of the crow family - clever, bold, adaptable and omnivorous - I doubt jays will go hungry. They just might need to look for some different foods in different places, so I wonder if that could mean an influx of jays to garden bird tables? In the same way, might we see squirrels launching a hunger-fuelled assault on our feeders?
Let us know what you see!
Have you spotted knopper galls on your local oak trees? Leave a comment and let me know.
We don't have oak in our locality but I have no sympathy for grey squirrels at all. We already have a population explosion. They were a nuisance until two years ago, mainly concentrating their attention on gnawing through bird feeders and carrying off seed and fat balls. Last year we suffered raiding parties of five at a time, stripping the green strawberries, each one carrying off several plums and apples every day. This year, they have already stripped all the plums, all apples apart from Bramleys, and all hazelnuts. They won't have hazelnuts to store, like in previous years - digging little holes all over our lawns. The reason being there are too many squirrels for their food supply to support. I imagine the squirrels that make it through the winter will be looking forward to some tasty meals of birds' eggs in early spring. I hope rspb does not encourage people to aid these designated pests.
The exact same here (just south of Stevenage): we started spotting this deformed acorns about a week or two ago – and promptly searched to find out what was wrong.
we seem to have goo acorns locally but a grey squirrel was busy picking all the peanuts off the bird table earlier this week. We get Jays occasionally coming into the garden from the surrounding fields, they seem to be able to smell peanuts from a mile away
Thanks for your comments. I've had a hard time finding any normal acorns! But I have noticed that the squirrels seem to be making inroads on the sweet chestnuts already - not sure if that's early?
Plenty around here in Shropshire too and it seems the Spangles (Neuroterus quercusbaccarum) have done very well too this year! There are still a good amount of gall free acorns about though so don't think our Jays or Squirrels will suffer too much!
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