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Poplar gall aphid Pemphigus phenax

Pemphigus phenax

Description

Pemphigus phenax is a gall-forming aphid that primarily targets black poplar (Populus nigra) and its cultivars. This monophagous species forms elongated, fusiform galls along the central midrib of leaves, which are typically reddish and yellowish. Galls have a slit-like opening along their underside, allowing aphids to exit. The species reproduces parthenogenetically during its primary lifecycle and completes its development within these galls.

Infestations can weaken trees by reducing leaf functionality, affecting photosynthesis and leading to reduced growth. Additionally, the galls diminish the aesthetic value of ornamental and urban trees. Pemphigus phenax is distributed across Europe and is most active during the summer months.

Symptom

On infested leaves, reddish, spindle-shaped galls form along the midrib, significantly thickened with a slit-like opening on the underside. The galls disrupt the smooth appearance of the leaf.

Tree Species: Poplar

Part of a plant- attacked: Leaf / Needle

Pest significance: Less harmful

Pest Category: Insects

Invasive Species: No

Present in EU: Yes