After last Sunday’s local meander I wrote on social media:

A lesson for me in the importance of recording: I’ve walked past this grapevine many times recently & noticed the galls on its leaves. Today I finally took photos, figured it’s caused by the mite Colomerus vitis & found there are NO Welsh records, tho’ it must be out there somewhere.

I’ve since checked the only other publicly accessible grapevine I know of locally and found that it, too, has these galls on its leaves so I was right to assume that this is something that has simply been overlooked and not recorded by anyone who’s noticed it. As well as there having been no previous Welsh records, there are very few records from elsewhere in the UK, which I assume is also under-recording, not scarcity.

The galls, which appear as lumps and bumps on the upper side of the leaves, are caused by the miniscule mite Colomerus vitis. These mites inhabit the felt-like surface of the galls on the underside of the leaves, a surface that starts out white but gradually browns over time. The vines I’ve looked at are covered in bunches of grapes and the plants themselves look very healthy so, presumably, the galls are having little affect on the plants’ productivity.