All About Galls 

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The Study of Galls is known as Cecidology

Galls can be caused by fungus, bacteria, mite, fly, midge, moth, wasp or beetle larvae. The plant species can have several different gall species on different parts of the plant - leaves, twigs, buds, roots, flowers and catkins, often each caused by a different agent and occasionally a gall can appear on another gall!

Nail Galls on Lime


Key ....Wasp / Sawfly......Mite.....Fungi......Nematode ......Fungi......Bacteria 



 Oak Quercus

Common Spangle Gall

 A Gall Wasp Neuroterus quercusbaccarum
 Oak Quercus

Silk Button Spangle Gall

  A Gall Wasp Neuroterus numismalis
 Oak Quercus

Knopper Gall

Gall WaspAndricus quercuscalicis
 Oak Quercus

Marble Galls

 Gall Wasp Andricus kollari
 Oak Quercus

Currant Gall - : on underside of oak leaves.

Gall Wasp (Sexual) Andricus quercusbaccarum
Oak Quercus

Oak Apple

A Wasp  Biorhiza pallida
Oak Sessile or Pedumculate

Acorn Cup galls

Acorn Cup galls Wasp Andricus grossulariae
Oak Sessile or Pedumculate

Cola Nut Galls


Gall Wasp Andricus lignicola

The Red-Pea Gall or Red Currant Gall

 A Wasp Cypnips divisa


Sessile Oak

Artichoke or Hop Gall

 Gall Wasp Andricus fecundator

Ash Flower Gall (mite)
Cauliflower Gall Mite

Mite  Eriophyes fraxinivorus
Birch Witches Broom Gall Fungi Taphrina betulina
Aspens  Galls of : Aspen  
Willows  Pea Like Red Gall  Pontania viminalis

Willow Red Gall

A Sawfly Pontania proxima

Alder Tongue

A Fungal Plant Pathogen Taphrina alni
Alder Alnus glutinosa

Alder Leaf Mite Gall

Gall Mite Eriophyes laevis

 Robins Pincushion or Bedeguar Galls

 A Cypnid Wasp Diplolepis rosae
Dog Rose Gall Wasp Diplolepis eglanteriae/nervosa
   Spiked pea galls  Diplolepis nervosa
 Bramble  Bramble Gall Wasp  Wasp Diastrophus rubi
 Common Lime

Nail Galls

  A Mite Eriophyes tiliae

Nettle Cluster Cup

Nettle Clustercup Rust Puccinia urtica

Meadow Sweet Gall

A Rust Triphragmium ulmariae



What is a " Gall " ?

Abnormal outgrowth on a plant that develops as a result of attack by insects or, less commonly, by bacteria, fungi, mites, or nematodes. The attack causes an increase in the number of cells or an enlargement of existing cells in the plant. Gall-forming insects generally pass the early stages of their life inside the gall.



Fig 1 & 2 Chambers within the Gall Containing the large developing Grub of the Cynip Wasp Diplopsis rosae

Gall wasps are responsible for the conspicuous bud galls forming on oak trees, 2.5–4 cm/1–1.5 in across, known as ‘oak apples’. The organisms that cause galls are host-specific. Thus, for example, gall wasps tend to parasitize oaks, and sawflies willows.

The ensuing "Gall" also becomes home for an elaborate ecosysyem in itself with other wasps often involved capitalising on the "fruits of the Gall" known as inquilants.These other species of wasp larvae will make use of the gall. There are the species that do not form their own galls but just utilize those already formed by others, these are the inquilines

Galls are relatively common however they are not often noticed and because of this only a few have common names, manyspecies are known only by their scientific name.

The Common and Silk Button Spangle Gall are found on our common Oak (Quercus robur). They are produced by a tiny Cynipid wasp which goes through a complicated life cycle using two stages of development.

Things begin in June when a generation of both Male & Female wasps hatch from Currant Galls. The adults mate and the female lays fertilized eggs on the underside of the Oak leaves. These cause the creation of the Common Spangle Gall in which the grub matures. The Spangle Galls fall from the leaves in September and the wasp continues to grow within the leaf litter. In April they hatch to produce a female-only generation. These start the cycle again by laying eggs on Oak flowers which develop into the Currant Galls.

Other species of Cynipid wasps produce different kinds of gall and have different life cycles. One example is the Knopper Gall which uses two different species of Oak (Quercus robur & Quercus cerris) and two years to complete its cycle.

English Oaks can have > 56 species living on them, including the Marble gall ( These are caused by a wasp called Andricus kollari, while the illustrations below shows three different spangle galls on the underside of oak leaves.

LAST UPDATED 04-Jan-2015 3:53 PM


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