An abnormal outgrowth of tissue which can appear on any part of a plant, caused by insects, bacteria, fungi, nematodes, or mites. The precise infecting agent is often, but not always, identifiable from the type of gall. Common examples are oak-apples and the pincushion galls of roses.
Galls or plant galls are proliferations and modifications of plant cells and can be caused by various parasites, from fungi and bacteria, to insects and mites. Galls are often very organised structures and because of this, the cause of the gall can often be determined without the actual agent being identified.
Creatures that induce galls
Insects
Insect galls develop under the influence of gall-inducing insects. In order to form galls, the insects must seize the time when plant cell division occurs at a high speed, the growing season, usually spring in temperate climates, but which can be extended in tropical latitudes. Although insect galls can be found on a variety of parts of the plant, such as the leaves, stalks, branches, buds, roots or even flowers and fruits, gall-inducing insects are usually species-specific and sometimes tissue-specific on the plants they gall.
Gall-inducing insects include gall wasps, gall midges, aphids, and psyllids.
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Andricus foecundatrix |
Andricus quercuscalicis |
Andricus quercuscalicis |
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Eucalyptus leaf gall |
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