How to recognize horse chestnut scale

The horse chestnut scale, Pulvinaria regalisbelongs to the group of wooly aphids. The females are brown and have an oval- and spherical body shape. The eggs are deposited in white wooly egg sacs which are formed in late spring and early summer on the tree trunk. During summer the eggs will develop in young crawlers, which move towards the leaves where they settle and grow until fall. Before the three sheds its leaves, the scales move to the branches where they will remain during winter. During winter they barely feed. Young stages reside, depending on the season, on the leaf, petiole or branch. Adult stages can be found on the tree trunk. 

Horse chestnut scale damage

The place of origin is probably Japan. During the sixties the pest was first observed in Europe. The scale has since been observed in France, Belgium, Germany and England and its living area is still spreading. The horse chestnut scale has many host plants, but is mostly found on chestnut and linden trees in urban areas.  

Damage is mainly cosmeticLarge amounts of honeydew are produced during heavy infestations. The honeydew acts as a growth medium for black sooty mold fungus which will turn the leaves black, which in turn hampers photosynthesis. 

Horse chestnut scale Pulvinaria regalis
Horse chestnut scale

Life cycle horse chestnut scale

  • 1000 eggs per female
  • young stages light brown, adult stages round
  • white egg masses formed in June/July
  • young stages reside on leaf, petiole or branch
  • adult stages reside on trunk

Host plants horse chestnut scale

  • maple
  • chestnut
  • linden tree
Our products against

Horse chestnut scale

EXOCHOMUS QUADRIPUSTULATUS against pulvinaria scale

EXOCHOMUS
QUADRIPUSTULATUS

Effective against
– Several soft scales
– Several (woolly) aphids

COCCOPHAGUS SCUTELLARIS

Effective agains
– Many different soft scale species

Common soft scale species

Brown soft scale
Hemispherical scale
Black
scale

Horse chestnut scale
Hydrangea scale
Cottony camelia scale