Oak Artichoke Gall Wasp

Andricus fecundator

Oak Artichoke Gall Wasp

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An artichoke gall produced by a Andricus fecundator Oak artichoke gall wasp
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Oak Gall Wasps are tiny gall-forming insects that look very similar to flying ants. Gall Wasps belong to a highly specialised group of wasps known as parasitoids who require a plant host to survive. Galls form directly from the presence of an organism in or on the plant. In most cases, galls won't cause permanent damage to plants, and some years can be worse than others. Gall Wasp eggs are laid in the shoot tips of new leaves in English and Sessile Oak. Plants begin to rapidly-produce cells, and growth becomes malformed. Plants produce an artichoke-like structure, which homes the wasp larvae.
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Gall wasps cause plants to produce abnormal tumours, known as galls.
Plant galls provide a home and food for many other insects.


Adults: These wasps are tiny and elusive and rarely seen. Galls are a much easier means of identification, as they can be unique to the insect and plant. The gall wasp eggs and larvae remain inside the plant and gall. Galls: These wasps produce two generations of larvae each year. Each generation creates a different gall type. The first generation of young cause artichoke galls to arise. As the name suggests, they look very similar to artichokes. They're green and found on the younger tree branches. Later in the year, the alternate generation of wasps produce galls in male catkins. These galls are less conspicuous in appearance.


Abnormal, artichoke-shaped tumours will protrude from the younger branches in infested oak.












Biological treatment

This wasp will not impact the longterm yield of trees, but the galls it produces may be unsightly. Gall wasps seem to be more frequent in some years than others, so trees usually have periods to recover.

Chemical treatment

Insecticides are unlikely to work on this wasp.


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