The wildlife and wild places of Leicestershire and Rutland
All images on this website have been taken in Leicestershire and Rutland by NatureSpot members. We welcome new contributions - just register and use the Submit Records form to post your photos. Click on any image below to visit the species page. The RED / AMBER / GREEN dots indicate how easy it is to identify the species - see our Identification Difficulty page for more information. A coloured rating followed by an exclamation mark denotes that different ID difficulties apply to either males and females or to the larvae - see the species page for more detail.
The British Plant Gall Society define a gall as ‘an abnormal growth produced by a plant or other host under the influence of another organism. It involves enlargement and/or proliferation of host cells, and provides both shelter and food or nutrients for the invading organism'. (https://www.britishplantgallsociety.org/)
Organisms that cause galls to form on plants encompass almost the entire spectrum of life – from viruses and bacteria, through Protozoa, fungi and allies, slime-moulds, nematodes, mites, aphids and psyllids, flies, beetles, moths, sawflies and wasps, and even a few algae and vascular plants. The organism that causes a gall is usually very difficult to identify, but often the gall can be identified. However, some galls are hard or impossible to identify, and it may be necessary to find the gall-causer and get expert help. The presence of parasitoids, inquilines or other organisms sheltering or feeding inside an occupied or vacated gall can be misleading, and it is common to find atypical specimens or chimaera formed by two or more organisms in close proximity - usually these can't be identified.
When recording galls, always start by identifying the host plant accurately and make sure you have included information on the host in the notes attached to your record. Most species of galls are specific to a host, and this is always the first step in identification.
Facebook Group: British Plant Galls
The Field Studies' Council's Aidgap guide by Redfern, M. & Shirley, P. (2023) ‘British Plant Galls’ (3rd edition). FSC is recommended. The BPGS Facebook group can help with identifying galls. Photos can be found on the BPGS website or on these northern European websites:
Pflanzengallen - Comprehensive guide to galls of Germany.
Plantengallen.com - English-language version of Dutch site.
Volkers Pflanzengallen - Volker Fäßler’s gall website (in German).
Leafminers and plant galls of Europe - Dr. Willem N. Ellis' website (‘Bladmineerders’).
An excellent account of the ecology and biology of galls is in Redfern, M. (2011) Plant Galls. Collins New Naturalist.
In the accounts below, there are sometimes two or more Red-Amber-Green or 'RAG' ratings - one or two referring the gall, and one to the gall-causer. Galls usually have a lower 'RAG' rating then the causer. Click on the species to find out more.
Gall Aphids & Bugs
All gall-causing Hemiptera, or true bugs, are in the Sternorrhyncha sub-order (aphids and adelgids, psylloids and scale insects).
True Aphids have complex life-cycles with alternating parthenogenetic and sexual egg-producing generation, sometimes involving two host species. Fertilised eggs hatch in spring into a nymph which develops into a female 'fundatrix'; she is viviparous, producing live young parthenogenetically, and often wingless ('apterous'). She is the foundation of the population over summer. Later in the year, males and females are produced, which mate; the female lays an egg which overwinters before hatching in spring to take advantage of new nutritious growth on the host plant. Winged adults or 'alates' are produced in those species that have their alternate generation on two different host species, and other 'morphs' or different body-forms can also occur.
The fundatrix of some aphid species produces galls which protect the summer population - these are often leaf folds or rolls such as Eriosoma ulmi, on Elm, or bladders such as Eriosoma lanuginosum or Tetraneura ulmi, also on Elm. Pemphigus spp. cause pouch and spiral galls on poplars. Aphids inside the galls are often covered in wax or wool.
Many aphids do not produce galls, but will cause distortion of leaves and shoots of their host, sometimes called a 'pseudogall'. These may be mistaken for galls, but do not show the enlargement or proliferation of plant tissue caused by the gall-organism.
Adelgids or woolly conifer aphids are related to true aphids. They cause pineapple galls on the terminal and axillary buds of spruce trees (Picea). Some species need another conifer host to complete their life-cycle; other live on the same host and have lost the sexual generation completely (as with the common Adelges abietis).
Psylloidea includes the families Psyllidae, Triozidae and Liviidae, collectively known as Psyllids or jumping plant lice. Galls include shoot-tips galls such as Psylla (Spanioneura) buxi on Box, pit galls such as Trioza remota on oak, where the nymph can be seen in a hollow underneath the leaf, and leaf folds and pouches such as Lauritrioza alacris on Bay and Trichochermes walkeri on Buckthorn. Most are host-specific, but Livia junci causes phyllanthy on a variety of rushes.
Some scale insects (Coccoidea) produce galls on the twigs of their hosts.
Further information about aphid, psylloid and adelgid life-cycles can be found on https://influentialpoints.com/
- pit-galls on oak twigs caused by scale insect
- Galls on White Currant form of Ribes rubrum
- Galls on Mugwort
- Galls on crab-apple
- gall on Apple
- on English Elm - 2nd VC55 record
- gall on elm leaf
- tenanted galls on Fat-hen
- Galls on Juncus articulatus
- on petiole of Lombardy Poplar
- on a hybrid Black Poplar
- gall on Lombardy Poplar leaf
- petiole gall on Lombardy Poplar
- gall on Box
- gall on Ash
- gall on Norway Spruce
- gall on Elm
- galls on Hybrid Balsam Poplar
- gall on Bay (Laurus nobilis)
- Gall on Buckthorn
- gall on Red Valerian - 1st for VC55
- galls on Pedunculate Oak
- nymph in hollow
on underside of leaf
- galls on nettle
Nearly all wasp galls in the UK are caused by wasps in the family Cynipidae, and most are on Oak, with a few on Rose and a few on other herbaceous species. Life-cycles increase in complexity from the galls on Bramble (Diastrophus) and herbaceous species (e.g. Aulacidea, Phanacis, Liposthenes), to more complex Diplolepis, which gall roses, to the Oak gall wasps (e.g. Andricus, Cynips, Neuroterus) with the most complex life-cycles.
Some rarely recorded galls on grasses (Tetramesa) and one introduced Eucalyptus gall (Ophelimus) are caused by chalcid wasps.
Oak cynipid wasps have alternating sexual/asexual generations, or ‘cyclical parthenogenesis’. Typically, the gall formed by the females of the sexual generation appears in spring/early summer, and is on a different part of the oak to the later asexual (or agamic) generation. In many species, the sexual galls are recorded less often than the asexual galls, which are often larger and persist longer. (An example of an exception to this is the oak-apple, Biorhiza pallida, which is the sexual gall). Often the 2 types of gall are a very different shape, and originally some were thought to be different species; in some species, the sexual gall has not been found. Some introduced species form sexual galls on the non-native Turkey oak and asexual galls on native oaks – e.g. Andricus kollari.
The first generation sexual gall is produced in spring by an asexual female that lays eggs parthenogenetically, without them being fertilised by a male. The females are of two kinds; those that lay eggs which produce male wasps, and those that produce females. From this gall, the second generation of sexual wasps emerges, both male and female; these mate, and the females then produce the asexual galls later in the year.
In the accounts below, asexual and sexual galls may have different 'Red-Amber-Green' (RAG) ratings - click on the species account to check. The gall most often recorded, with the lowest RAG rating, is shown first.
- old gall on bramble stem
- gall on bramble stem
- galls on Ground-ivy
- Gall on a Hawkweed
- gall on common cat's ear
- on Tormentil stem
- Smooth Pea Galls on Dog-rose
- sputnik galls on Dog-rose
- Gall on Dog Rose
- galls on Dog-rose
- agamic galls on oak
- agamic galls on oak
- asexual (agamic) gall on Oak
- vacated sexual gall on oak twig
- sexual generation gall on Oak - upper surface of leaf
- old agamic gall after the inner gall has been expelled
- agamic gall on Pedunculate Oak
- Agamic gall on Oak
- Agamic gall on oak bud
- galls on oak
- Asexual generation gall on English Oak
- sexual generation galls on Turkey Oak catkins