it will be a grub of either a sawfly or a leaf miner. with out seeing an actual culprit it is impossible to say.

I agree. caterpillars of some kind. I could feel the Autumn chill in the air so the season is winding down anyway. I wouldnt do anything at all. All the leaves will be gone soon

Thank you both. The way the leaves have been eaten is like the damage done by the gooseberry sawfly. I didn’t know sawflies attacked geraniums as they haven’t before, but perhaps it’s the weather conditions.
Thank you again.

Whatever is eating the leaves does it with artistic flair. It looks like one of those lace doilies my grandmother would spend hours and hours knitting.

My blue geraniums are munched every year by sawfly maggots and they look very unsightly. The maggots are black/grey wriggly horrors and I just cut off the affected leaves.

You’re right there, B. I remember those too but ours weren’t knitted, they were crocheted.

My geranium is, I think, pheasants eye and I have cut the leaves off as there were so unsightly. What’s more troubling is that the maggots are now attacking a young silver leafed Fatsia, nearby. Can’t cut all those leaves but, hopefully, if there is nothing else round the little devils will clear off somewhere else.