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Rapid Assessment of the need for a detailed Pest Risk Analysis for Parthenolecanium fletcheri (Cockerell) (Cockerell)


This rapid assessment shows: 

Risk of entry – unlikely

 The main route of entry is likely to be on growing ornamental plants from countries where the scale has been reported. It has, however, it has only been found on one occasion despite the popularity of Cupressaceae in the horticultural trade. Detection of early instars is difficult, particularly when present at low density. The scale may only be observed when mature specimens are present or numbers have built up to such a density that they are already causing conspicuous damage. 

Risk of establishment – on Cupreassaceae outdoors is very likely, on protected plants moderately likely. Fletcher scale has the potential to naturalise widely in England and Wales, wherever its host plants occur, as it has been breeding outdoors in London for seven years and is present in Canada and Scandinavia. The winters of 2009/10 and 2010/11 were the coldest in southern England for decades but the scale survived outdoors. It has been found infesting protected potted plants in Lithuania and there appears to be no reason why it could not establish under protection in the UK. 

Rate of spread – very slow naturally, slow in trade 

Spread is most likely to be with infested plants in trade. Economic impact – may have a small impact to indoor ornamentals It is recorded as a pest of Taxus and Thuja in N. America, but does not appear to be an economic pest in western Europe. It may have a small impact on the aesthetic quality and market value of Cupreassaceae but there is little data available to quantify the economic implications. 

Endangered area – outdoors throughout Britain 

Risk management – may be controlled by using the same products used for other coccids In the absence of phytosanitary measures the scale is likely to continue to enter the UK. 


  • Parthenolecanium fletcheri


  • Cupressus
  • Juniperus
  • Platycladus orientalis
  • Taxus
  • Thuja
  • Tsuga


Type File Size
Pest Risk Analysis Download 214,49kB

PRA Area

  • United Kingdom