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Andricus quercusramuli

Cotton wool gall wasp

Description

The sexual generation develops in cotton wool-like mass 15-40 mm across which develops on a catkin and contains 5-20 inner galls. The gall is white when young, later turning brown. Larvae inside the gall mature and emerge in late June. The females then cause the alternate asexual generation galls in oak buds. More frequent in warmer oak forests in southern parts of Europe.

Symptom

The sexual generation develops in cotton wool-like mass 15-40 mm across which develops on a catkin and contains 5-20 inner galls. 

Tree Species: Oak

Part of a plant- attacked: Branch

Pest significance: Less harmful

Pest Category: Insects

Invasive Species: No

Present in EU: Yes