Scale insects are

Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding.

• Convex, oval, dark brown ‘shells’, 3-6 mm long, occur on the woody stems
• It is not unusual to find this scale on yew, only heavy populations may affect vigour and cause defoliation
• A black sooty mould often develops on the sugary honeydew, that is excreted by the insects as they feed on
  Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding.

  sap and deposited on leaves and stems

• Light populations of yew scale are of little consequence on yew trees, indeed they are normal for a healthy yew and can usually be tolerated; well-tended, smaller, healthy plants are able to tolerate light populations of these insects
• Encourage predators in the garden; yew scale is a food source for some ladybirds, and other predators. Natural enemies will often keep populations of this insect in check