Thank you!They will feed on the young needles when the buds open discolouring them very quickly.
They can be blasted off with water but it takes persistence and you need to develop the technique, it’s not easy. Dusting with DE when they are very young and haven’t grown the white fluff yet works ok. Small window of time there just as buds are elongating. Insecticidal soap during this stage also works very well but the soap may strip the protective covering off young emerging needles leaving them more susceptible to a needle rust that’s very common with dougies. I’m not really sure that’s the case but have thought I noticed a co-relation before, maybe it was just weather.
Part of their lifecycle is migratory with wings so...distance may not matter much.