Oak Gall Wasp

Andricus spp.

Oak Gall Wasp

Andricus fg13 by Fritz Geller-Grimm (CC BY-SA 3.0)
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A gall wasp belonging to the genus Andricus on a leaf
Andricus fg13 by Fritz Geller-Grimm (CC BY-SA 3.0)
1 of 6
Oak Gall Wasps are tiny-black gall-forming insects that look very similar to flying ants. Andricus wasps belong to a highly specialised group of wasps. Gall Wasp eggs are laid in the shoot tips of new leaves. Plants begin to rapidly-produce cells, and growth becomes malformed. Plants produce galls resembling something similar to an artichoke or conker, which homes the wasp larvae. This particular group of wasps specialise feeding on Oak, with some trees provide homes to over 30 different species! Each species of gall-wasp will produce a unique gall on the infested tree.
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Traits

Gall wasps cause plants to produce abnormal growths, known as galls.
Galls won't permanently damage plants.

Appearance

Adults: Adult wasps are sometimes compared to ants due to their small size and black-brown colouration; some are even wingless! They're tiny so it's unlikely you'd see them. Wasps are normally identified by the galls produced on the infested plant. The gall wasp eggs and larvae remain inside the plant and gall. Galls: Andricus foecundatrix is an Oak-gall wasp that generates an 'artichoke gall'. Gall production is initiated by a female injecting her eggs into the leaves of the Oak host. Galls are incredibly diverse and differ significantly between species. Generally, they look like protruding abnormalities or swellings, that extends from areas of new growth.

Symptoms

Abnormal tumours become evident near areas of new growth in oak trees. Galling-behaviour can sometimes result in reduced yields.

Activity

Diurnal

Personality

Order

Hymenoptera

Family

Cynipidae

Metamorphosis

Complete

Distribution

Worldwide

Biological treatment

This wasp will not impact the longterm yield of trees, but the galls it produces may be unsightly.

Chemical treatment

Insecticides are unlikely to work on this wasp.

Attracts

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