Register with us or sign in
A systemic insecticide will deal with it, but you really have to spray before they appear. They are harmless, just disfiguring.
As they are actually inside the leaves, contact insecticides like that won't really work. A systemic insecticide would, but that means you would be eating the chemical when you eat the kale, so that's not on either. If there are not too many, you can squash them within the leaf between finger and thumb - where they are within the damaged areas is often visible.
Thank you BobTheGardener I shall squash them tomorrow! Should I take any measures to prevent anymore appearing after this?
There's not much you can do, but assuming it's Scaptomyza flava (a small fly about 2.5mm long), I think it's only active at certain times of the year (now being one of them), so fleecing the crop from midsummer is probably the best bet. Apparently this particular species is becoming a serious pest for commercial brassica growers, so it might be worth googling.
Thank you for your help. Hopefully I can now prevent any further damage. Many thanks BobTheGardener.