I have been seeing a lot of Scale Insect problems on Hollies in the last few weeks. The holly may have a dark black appearance on the old foliage with a cottony mass on the leaf surface. The black appearance is called sooty mold and is the result of fungus growing on the insects frass. The scale insect is generally protected by a shell and is generally diffucult to kill. The difference being right now the insect eggs have hatched and are moving out from under their protected shell. This is called the crawler stage and the insects are at their most vulnerable. Click here for control options.