Galls or cecidia are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or warts in animals. They can be caused by various parasites, from viruses, fungi and bacteria, to other plants, insects and mites. Plant galls are often highly organized structures so that the cause of the gall can often be determined without the actual agent being identified. This applies particularly to some insect and mite plant galls. The study of plant galls is known as cecidology.
Gall wasps, also incorrectly called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this generally very small creature (1–8 mm) are known worldwide, with about 360 species of 36 different genera in Europe and some 800 species in North America.
Andricus kollari, also known as the marble gall wasp, is a parthenogenetic species of wasp which causes the formation of marble galls on oak trees. Synonyms for the species include Cynips kollari, Andricus quercusgemmae, A. minor, A. indigenus and A. circulans.
Neuroterus is a genus of gall wasps that induce galls on oaks in which the wasp larvae live and feed. Some species produce galls that fall off the host plant and 'jump' along the ground due to the movement of the larvae within.
The red-pea gall or red currant gall develops as a chemically induced distortion arising from the underside of the mid-rib of a vein on Quercus species and it is attached by a short stalk or peduncle. The red-wart gall is the sexual phase of the same species.
The common spangle gall on the underside of leaves and the currant gall on the male catkins or occasionally the leaves, develop as chemically induced distortions on pedunculate oak, or sessile oak trees, caused by the cynipid wasp Neuroterus quercusbaccarum which has both agamic and bisexual generations.
Neuroterus numismalis is a gall wasp that forms chemically induced leaf galls on oak trees. It has both bisexual and agamic (parthenogenetic) generations and forms two distinct galls on oak leaves, the silk button gall and blister gall. The galls can be very numerous with more than a thousand per leaf.
Cynips is a genus of gall wasps in the tribe Cynipini, the oak gall wasps. One of the best known is the common oak gall wasp, which induces characteristic spherical galls about two centimeters wide on the undersides of oak leaves.
Cynips quercusfolii is a gall wasp species in the genus Cynips. The species is important for the production of commercial nutgall formed on Quercus lusitanica . Galls are located on the underside of leaves, with the majority of galls being on the second and third veins from the petiole of the leaf.
Andricus grossulariae is a gall wasp species inducing agamic acorn cup galls on oak tree acorn cups and sexual phase galls on catkins. Synonyms include Andricus fructuum, Andricus gemellus, Andricus intermedius, Andricus mayri and Cynips panteli.
Cynipini is a tribe of gall wasps. These insects induce galls in plants of the beech and oak family, Fagaceae. They are known commonly as the oak gall wasps. It is the largest cynipid tribe, with about 936 to 1000 recognized species, most of which are associated with oaks. The tribe is mainly native to the Holarctic. Cynipini wasps can act as ecosystem engineers. Their galls can become hosts of inquilines, and the wasps themselves are hosts to parasitoids.
Andricus inflator is a species of gall-forming wasps, in the genus Andricus, which has a sexual and an asexual generation, producing two different galls. The wasp was named by the German biologist Theodor Hartig, in 1840 and is found in Europe.
Andricus dimorphus, also called the clustered midrib gall wasp, is a species of oak gall wasp in the family Cynipidae. Galls in which the larvae live and feed are formed in clusters along the midrib on the underside of oak leaves.
Andricus quercuspetiolicola, also called the oak petiole gall wasp, is a species of oak gall wasp in the family Cynipidae. Galls in which the larvae live and feed are formed along the midrib or petiole of white oak leaves.
Cynips quercusechinus, the urchin gall wasp, is a species of gall wasp in the family Cynipidae. It induces its galls, which resemble sea urchins, on the leaves of oak trees. These galls are about 10mm in diameter. The galls fall with the leaves in autumn, and the larvae inside of them emerge as adults in the spring.
Druon ignotum is a species of gall wasp in the family Cynipidae.
Andricus crystallinus, also known as the crystalline gall wasp, is a species of gall-forming wasp in the genus Andricus. Its galls are pink and covered in hairs that are white, red, or brown. These galls are often massed together in clumps that can cover the underside of leaves. Individual galls are 12-14 mm high, 7 mm across, and have a single chamber for larvae. The unisexual female generation emerges in late winter, and the bisexual generation of males and females emerges in March. They are found in all species of oaks in California.
Andricus gigas, also known as the saucer gall wasp, is a species of gall-forming wasp in the genus Andricus. It induces galls on the leaves of scrub oaks, blue oaks, and Engelmann oaks. The galls produced by its all-female generation, which emerges in winter, are 3-4 mm wide, circular with raised edges. They are red, pink, brown, or purple. The larval chamber exists as a raised bump in the gall's center. The bisexual generation produces galls that are brown and cone-shaped.
Amphibolips quercuspomiformis, also known as the apple gall wasp or live oak apple gall wasp, is a species of gall wasp. It induces galls in coast live oak and interior live oak trees. Like many gall wasps, it has two alternating generations: a parthenogenic generation, and a bisexual generation. The galls formed by the all-female parthenogenic generation are spherical, up to 40 mm in diameter, and covered with short spines. They form on stems and are green or red when new, then turn brown. The galls formed by the bisexual generation are small, shaped like toadstools, and occur on leaves.
Andricus pattersonae, also known as the plate gall wasp, is a species of gall-forming wasp in the genus Andricus. Their hosts are among the white oaks grouping of oaks, with blue oak being common.
