Cushion scale

Scale insects are sap

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. 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.

Cushion scale is a sap-sucking insect that feeds on the foliage of mainly evergreen trees and shrubs, especially camellia, rhododendron, Trachelospermum, Euonymus japonicus and holly.

• The scale does not usually affect the vigour or flowering of it's host plants, it does however produce a sticky honeydew excrement
• A heavy coating of a black, non-parasitic fungus known as sooty mould can grow on honeydew on the upper leaf surface. This develops over the winter months and can persist into the summer
• Yellowish-brown, oval scale insects up to 3 mm (1/8 in) long can be seen near the veins on the undersides of the leaves
• Rectangular white waxy egg masses, up to 10 mm (almost ½ in) long and 2-3 mm (1/8 in) wide, are produced by the adult scales in spring and early summer. The remains of these egg masses can persist on the foliage throughout the year

• 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
• On small plants sooty mould can be removed by wiping the foliage with a damp cloth
• Adult scales and egg masses can be removed when seen (spring and summer) but this may not reduce large populations

• There is one generation of cushion scale a year with eggs hatching in late June-July
• The scales suck sap
  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. and excrete a sugary honeydew that coats the upper leaf surface, allowing sooty moulds
  These look like black or brown powder on upper leaf surfaces. They grow on sugar-rich honeydew produced by sap-sucking insects, or occasionally on sugary substances produced by the plant itself. In most cases, sooty mould is a tell-tale sign of an insect infestation. to develop, especially during the winter
• The size of the population on your plant can vary considerably from year to year. In mild wet winters, populations of overwintering nymphs may be reduced by a (insect pathogenic) fungal infection