Hi chicky and Kay thanks for suggestions. I've no leaves to photograph at moment and have never got round to joining RHS maybe this year. Yes Kay sawflies have come to my attention on other sites but I don't know if they target salvia's either and if they do how to go about dealing with them maybe someone else out there does know !
To reawaken this thread, I'm suddenly having the same issue. Just wondering if a year on there are any more thoughts. Mine seem to start at the base of the leaves. I'm thinking, as it's so widely spread, its a breeding virus coming out a few years down the line.
Posts
https://forum.gardenersworld.com/discussion/547953/leaf-damage-whitefly-sawfly
I don't know if it's my tablet but unfortunately I can't see the photos that @Loxley posted ?
Unfortunately, many of the photos from old posts didn't survive when the site was updated several years ago, AnniD.