Last year I found about 15 of these scale insects on a holly stalk.
I didn't find out which type they were, but they were all dead females. They were about 3mm long but the white woolly looking excretion was actually covering and protecting their eggs and young. The males are apparently very tiny indeed.
Today I found some more (I presume they are also scale insects) on the Viburnum dawn. There were four of them, none with the woolly excretion, also 3mm but more rounded in shape and much darker in colour. I wondered if this was more to do with camouflage as it was a good match to the stalk.
Does anyone know what their actual purpose is, apart from to mate and die? And do they actually do damage to plants?