I have some dwarf Burford hollies that are about 5 years old and are all full of what appear to be houseflies and wasps. I looked it up and it appears they are drawn to some sort of secretion left by another pest that has infested the shrubs. The only thing I can see are some black spots on some of the leaves and there is some minor leaf droppage. I assume this is a fungus of sorts. I hit them with some neem oil since that targets a variety of pests and unlikely to harm the plant. The flies went away for a few days but they are back.
Any ideas on what the black spots are or any treatment suggestions? I suppose I'll keep spraying them with neem oil every week or so and hope for the best. I have some knockouts between the hollies and don't want them to get infested, too.
Thanks, Eric.