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Aceria erinea

Walnut leaf gall mite

Description

Numerous bulges appear on walnut leaves, different size and shape. The bulges are caused by a tiny mite, only 0.08–0.2 mm in size, hardly visible even through a magnifying glass. The pest overwinters on buds and colonizes sprouting leaves in spring. Its presence results in a formation of bulges on leaves and felt-like film (erineum) formed on the underside of leaves. The erineum creates a favourable habitat for the mite, sheltering its development from external effects. This pest has several generations per a year.

Symptom

Bulges on leaves and felt-like film (erineum) formed on the underside of leaves.

Tree Species: Walnut

Part of a plant- attacked: Leaf / Needle

Pest significance: Less harmful

Pest Category: Mites

Invasive Species: No

Present in EU: Yes

Seasonal frequency of occurrence

Seasonal frequency of occurrence