I have a very limited knowledge of scale insects (
i.e. those I've needed to recognise
), there are about 8,000 worldwide and many sub-tropical ones have established in temperate regions.
There's a brief summary at
Scale Insects
Mostly they do not have wings (although, I think, sometimes, the tiny males do
). The young scales overwinter in the soil or leaf litter and crawl up plants in the spring, feed on the sap, grow, mate, move down the plant to lay their eggs which are protected by the coat (armoured, waxy, whatever ... ) of the mother.
So, what you have is
possibly an early life stage crawling up the tree then settling itself to eat &c.. Perhaps someone else has a clearer idea?