Fluted scale is a sap-sucking insect that originates from Australasia but has become widespread in the warmer parts of the world, including the Mediterranean area. It is also sometimes known as cottony cushion scale, but should not be confused with cushion scale or woolly vine/currant scale. It was an uncommon insect in heated glasshouses in Britain but since the 1990s it has become established outside in sheltered places, especially in London.

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.

The adult flutted scales are flat, oval insects, 4-5 mm long and reddish brown in colour. The females are usually found perched on the edge of white waxy mounds in which eggs are deposited. These egg mounds have a distinctive grooved or fluted appearance, which is unlike any other scale species found in the UK. The young nymphs are oval and brownish but have a white waxy coating. Adults and nymphs can be found together all year round on the stems and foliage. Frequent host plants are Citrus, Acacia and Choisya but it can occur on many other woody plants.

Fluted scale sucks sap from a wide range of trees and shrubs. Heavily affected plants lack vigour and can be killed. A black sooty mould may grow on the insect's sugary honeydew excrement.

If you encounter this insect on indoor plants then please consult our page on indoor plants: sap feeders for indoor specific advice.

• When buying Citrus, Acacia or Choisya, check carefully to make sure they are free of fluted scale
• 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. In many parts of the world, an Australian ladybird known as the vedalia ladybird, Rodolia cardinalis, has been released as a biological control for fluted scale. This ladybird is not commercially available in Britain but it has been found in some parts of London. It probably arrived accidentally, along with the scale insect, on imported plants 
• Adult scales and egg masses can be removed when seen but this may not reduce large populations

Fluted scale has two or three generations a year, which overlap so both nymphs and adults can be found at the same time. The adult scales are mainly found on the stems, whereas young nymphs are mainly on the underside of leaves along the leaf veins. Each egg mound can contain several hundred eggs.