I have what seems a severe scale infestation on a lilly pilly hedge. Because the hedge is quite thick, it's not possible to spray white oil right through. What do I do?
treatment with a white oil spary either a home made white oil or an off the shelf, spray after the heat of the sun, a hadge could be quiet involved if all parts of the hedge are infected?
look for the ants they would have bought them in, so if you move the ants on then the scale will not prolificate and will over time disappear. you could lay some ant bait stations along the path of the ants (might be a recipe or 2 on our remedies page), or if you can find the nest target the nest, a regular daily dose of water will send them off hopefully to far enough away, you could use buckets of grey water.
there are commercial ant sands available, they work quiet well. for individual plants a smear of vaseline around the trunk will stop the ants, be sure the plant does not have contact at any other points as the ants will find this and bypass the vaseline.
Here is a link that might be useful: len's garden page