Panaphis juglandis

Large walnut aphid

Description

Panaphis juglandis (large walnut aphid) is a common aphid species that primarily infests walnut trees (Juglans spp.) across central and southern Europe, Asia Minor, and North America. Somethimes known also under the name Callaphis juglandis. This species overwinters as eggs laid on young shoots, which hatch in early spring. Colonies form predominantly on the upper leaf surface along the midrib, where they feed in dense rows. Viviparous females are yellowish-green, often with orange markings, while males have brown heads and thoraxes with yellowish abdomens bearing dark bands. The aphid's feeding leads to the secretion of honeydew, which fosters the growth of sooty mold, reducing the photosynthetic efficiency of leaves. Severe infestations can hinder tree growth, decrease nut production, and negatively affect the overall health and aesthetic appearance of walnut trees.

Symptom

Infested leaves show colonies of yellow aphids along the midrib, with visible honeydew accumulation, often leading to the development of dark sooty mold. Leaves may yellow and fall prematurely.

Tree Species: Walnut

Part of a plant- attacked: Leaf / Needle

Pest significance: Less harmful

Pest Category: Insects

Invasive Species: No

Present in EU: Yes