Horse chestnut scale

Pulvinaria regalis

Recognizing horse chestnut scale: 
The Horse chestnut scale, Pulvinaria regalis, belongs to the group of woolly aphids. The original distribution of the pest is probably Japan. In the sixties, the pest was first observed in Europe. It has since been found in France, Belgium, Germany and England. The area where the pest is found is still expanding. Young stagesare found on leaves, petioles or branches, depending on the season. Adult stages mainly occur on the trunk. The scale is observed on different plants, but is most common on chestnut and lime trees and increasingly in urban areas. The scales feed on plant juices. In the summer they are located on the trunk and later on the leaves of the trees. In the autumn they move to the branches, to avoid being dropped off with leaf drop in this season. In late autumn they move to the trunk of the trees, where they hibernate. In winter they barely feed. In late spring or early summer the characteristic white egg masses are formed on the trunk, from where during the summer the young crawlers develop. These young stages walk to the leaves, where they settle down and grow until the autumn.

Damage horse chestnut scale: 
Horse chestnut scale causes mainly cosmetic damage. At heavy infestations a huge amount of honeydew will be produced by the scales. In this honeydew the black sooty mould fungus starts growing which causes leaves turning black. 

lifecycle horse chestnut scale:

  • young stages bright
  • adult stages round, brown
  • from June / July striking white egg masses become visible
  • about 1,000 eggs per female
  • young stages on leaf, petiole or branch, depending on the season
  • adult stages on the trunk

host plants horse chestnut scale:

  • maple
  • horse chestnut
  • lime tree


Exochomus quadripustulatus:

E. quadripustulatus

Coccophagus scutellaris:

C. scutellaris