Posting for my daughter. She has moved into a house with a large garden full of overgrown shrubs which have been attacked by something! First noticed on a rhododendron and now spread to many other very large shrubs. The underside of the leaves are covered in a white maggot looking thing although new growth is still appearing. She has bought a spray hoping to eradicate it but I feel it is too bad to be able to do this and maybe should all be cut down (a huge job).