Dopluis en pulvinale dopluis - Parthenolecanium pomeranicum/Chloropulvinaria floccifera
Cap aphids are quite common on yew and, after heavy infestation and as a result of the excretion of honeydew by the aphids, can mar the plant by a black veil of sooty mould. This occurs mainly on the underside of the plant.
Damage:
The soiled needles cannot do enough photosynthesis and fall off .The plant then has severely reduced vigour.
Solution:
Treat with suitable insecticide against shell aphids see www.fytoweb.be
There are 2 times when you can tackle these cap aphids well, early spring after the first warm days and at the end of June when the larvae emerge from under the carapace