Felted-scale
Guides
Cryptococcus fagisuga
beech scale, woolly beech scale
Cryptococcus fagisuga is a felted scale insect and the initiating agent of beech bark disease, a complex disease affecting beech trees (Fagus spp.). Native to Europe, it was introduced to North America around 1890 and has since spread throughout the range of American beech. The insect feeds on phloem sap by inserting stylets into bark tissue, creating wounds that enable secondary infection by pathogenic Neonectria fungi. The combined damage from scale feeding and fungal cankers can girdle and kill trees over several years.