By Lindiloo
Spain 
I have lots of hebe shrubs in my garden and they have been infested by tiny black insects that live on the leaves and leave thousands of little white flakes on the back of the leaves. They also become encrusted on the stems so the stems turn brown in colour. They suck all the moisture out of the leaves which then fall off. This infestation came to our village about 3 years ago and has just spread from the public gardens to our private gardens. I have tried pesticides, washing up liquid, diluted bleach and all three together nothing seems to be shifting them. I have cut the shrubs down to the base and removed all the dead leaves and as soon as the plant grows there're back again. It is only the hebe shrubs that are affected, I don't know why. Can you help?
4 Jul, 2014
Answers
Thank for your help and I have uploaded photos as requested.
6 Jul, 2014
Scale infestation, having seen the pics. There's a Provado treatment (Provado Ultimate Bug Killer concentrate or spray) for scale which should work, but I don't know if its available there(assuming you actually are in Spain, which is what your flag says) - you need to spray the whole plant, right down to the basal, woody parts. Otherwise, you're stuck with trying to clean them off the woody parts with a wet, disposable cloth, preferably lightly moistened in methylated spirits, but this should not be applied to green parts.
7 Jul, 2014
Thanks Bamboo, yes I do live in Spain and although amazon won't deliver the product here, I now have picture and details of the product you mentioned so I will now go in search of it at the garden centres and hardware stores here and give it a try.
19 Jul, 2014
I'd like to see a photograph of the encrustation on the stems - it sounds like some sort of scale infestation, but if its a problem in the public areas, it may be that whatever passes for a local council, or whoever is responsible for gardening in the public area, knows what it is.
4 Jul, 2014