There are several species of diaspid scale in Britain that have a similar appearance and lifecycle. Adult female diaspid scales are covered by flat rounded whitish brown shell, about 2 mm in diameter, and occur on the leaves and stems of host plants. The narrow elongate adult males are usually covered with a fluffy white wax; they generally cluster together at the base of the leaves. No honeydew is produced. Reproduction occurs throughout the year.

Heavy populations can weaken plants and the scales and white wax produced by the males may be considered unsightly.

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

• 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
• Adult scales and egg masses can be removed when seen but this may not reduce large populations
• A 2 mm long black ladybird, Chilocorus nigritus. is available from some Biological control suppliers and can help manage these scale in glasshouses during the growing season
• Consider replacing severely affected plants 

Downloads

Biological control suppliers (pdf document)

Diaspid scales feed by sucking sap from the leaves and stems of orchids and other glasshouse plants. Scales are named for the waxy shell-like casing which covers most of their body. When mature, the females lay their eggs under the protection of this shell. The eggs hatch into small active nymphs, known as crawlers, which wander over the plant surface until they find a suitable place to feed. They then become immobile and begin to produce their characteristic scale covering.

It is the crawler stage of this scale insect that are mobile, they may travel quite long distances before stopping to feed, and can be spread by wind currents. Diaspid scales reproduce throughout the year on glasshouse plants.