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.

Heavily affected plants develop a yellowish mottling on the foliage and this may be followed by extensive leaf fall and dieback.

Male and female euonymus scales differ in appearance. The males are mainly on the foliage and are covered with narrow white elongate scales that are 2 mm long. The females mainly occur on the stems and are covered with blackish brown pear-shaped scales up to 3 mm long.

This scale has two generations a year with nymphs present in late spring and autumn.

The most susceptible host plant seems to be Euonymus japonicus but other evergreen and deciduous spindles can also be affected. Heavily affected plants may lose most of their foliage and suffer dieback. These plants sometimes recover but replacement may be necessary.

• Where possible tolerate populations of scale insects. Well-tended healthy plants are able to tolerate light populations of these insects
• Encourage predators  in the garden, some ladybirds, parasitoid wasps and some birds will eat scale insects. The native kidney spot ladybird, Chilocorus renipustulatus, specialises in feeding on scale insects and can naturally colonise affected plants reducing populations
• Adult scales can be removed when seen but this may not reduce large populations

Euonymus scale has two generations a year. The females deposit their eggs underneath their bodies. Nymphs of the first generation emerge in June and crawl over the plant in search of suitable places to feed. They reach the adult stage in mid-late summer and lay eggs that hatch in early autumn.