Rose's picture

Gall on English oak

Observed: 20th May 2009 By: RoseRose’s reputation in PlantsRose’s reputation in PlantsRose’s reputation in Plants
Galls on Quercus robur
Description:

Gall wasps are rarely seen (often no more than 5mm long), but their effects can be seen nearly everywhere because they are responsible for many plant galls. There are about 90 gall wasps in the UK and 42 of these are known to induce galls on Oak trees.

Identifications
Species interactions

No interactions present.

Species with which English Oak (Quercus robur) interacts

Comments

Martin Harvey's picture

Pea gall?

Hi Rose,

Looks like the gall might be Pea Gall, caused by the asexual generation of the wasp Cynips divisa. Not certain though, according to the key there is a similar but less common species, Cynips agama. If it is C. divisa it should be quite solid and will resist crushing, whereas C. agama is less robust.

Or I could be completely wrong and they are young versions of the Cherry Gall, Cynips quercusfolii, but if so they'll get a lot bigger!

Martin

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Entomologist and biological recorder

Rose's picture

I will follow up the identification tips.

Hi Martin,
I had a look in a book but wasn't really sure. I will return at some point over the next few weeks, and review their progress; firstly see if they get bigger! If not, then I may try and crush one of them, and see if it resists. I might feel a bit bad doing that though. I will report back on my findings. Thanks for the info.
Rose.

Rose