I have a mature pieris in my front yard that is heavily infested with scale. Many of the small twigs are entirely covered in them, they're on the underside of the leaves as well. There is sooty mold on all older growth. Leaves are mottled and dull. Last summer I pruned it to a more open, tree shape, cutting lots of internal dead twigs. Had read that might help, but it doesn't seem to have made a difference. While the plant doesn't look very healthy, it seems to be doing okay - flowered well this year and last, and is just starting to show the red spring growth. Is neem oil the only thing I can do? I have read to apply during the 'crawler stage', does anyone know when that is in zone 8, Vancouver BC? Or have any other suggestions for what I can do? Thanks!!