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

Scale insects are sap sucking true bugs belonging to several families in the Hemiptera. Typically the adults are immobile having a flattened or raised appearance, with no visible legs. They often look like a ‘scale’ on a leaf or stem, many species produce a white wax often covering egg masses. There are more than 100 species found in Britain, 26 of which have been introduced. More than 25 species can be found in gardens or on houseplants.

Juniper scale is often present on the foliage of susceptible conifers but are only a problem if a heavy infestation develops when there may be yellowing and die back of the foliage. Unlike many other scale insects this species does not produce honeydew. 

There can be other reasons for brown patches in conifers including insects such as the cypress aphid. Large populations of juniper scale often seem to develop on plants that are already suffering a lack of vigour for these other reasons.

• Where possible tolerate populations of scale insects. Well-tended healthy plants are able to tolerate light populations of these insects and so they do not necessarily require management
• Encourage predators in the garden, some ladybirds, parasitoid wasps and some birds will eat scale insects
• Heavily affected plants can be removed and replaced. Large populations of juniper scale often develop on plants that are already lacking vigour