Reaumur's aphid gall

Systematic position and biology
Patchiella reaumuri is a species of aphid belonging to the order Hemiptera and the family Aphididae. It is recognized for its unique ability to induce the formation of galls on its host plants, providing a protected environment for its colonies to thrive and feed undisturbed by predators.

Host plants
The primary host for this species is the alder buckthorn (Frangula alnus). By selecting this specific shrub, the aphid completes its complex life cycle, heavily relying on the host's physiological response to its feeding to create the necessary gall structures.

Life cycle and development
The life cycle of Patchiella reaumuri is strictly synchronized with the phenology of the host plant. The aphids overwinter as eggs on the bark of twigs. As spring arrives, the emerging nymphs begin feeding, which triggers the development of galls on the leaves, where subsequent generations develop throughout the spring and summer.

Damage and pest status
The infestation is characterized by the appearance of thickened, curled, and often discolored leaf margins, which are the galls. Inside these structures, the aphids drain sap, leading to stunted shoot growth, chlorosis, and general plant weakening, which can significantly affect the overall health of the shrub.

Control measures
Effective management of this pest requires an integrated approach:

• Regular inspection of buckthorn plants during the early spring to detect emerging galls.
• Pruning and removing infested foliage or branches to reduce the localized population before the aphid migrates or completes its cycle.
• Application of systemic insecticides at the very beginning of the season when nymphs are active and before the galls have fully formed and protected the colony.