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 traditionally calledgallflies, 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 are known worldwide, with about 360 species of 36 different genera in Europe and some 800 species in North America.
Andricus quercuscalicis is a gall wasp species inducing knopper galls.
Andricus foecundatrix is a parthenogenetic gall wasp which lays a single egg within a leaf bud, using its ovipositor, to produce a gall known as an oak artichoke gall, oak hop gall, larch-cone gall or hop strobile The gall develops as a chemically induced distortion of leaf axillary or terminal buds on pedunculate oak or sessile oak trees. The larva lives inside a smaller hard casing inside the artichoke and this is released in autumn. The asexual wasp emerges in spring and lays her eggs in the oak catkins. These develop into small oval galls which produce the sexual generation of wasps. A yew artichoke gall caused by the fly Taxomyia taxi also exists, but is unrelated to the oak-borne species. Previous names or synonyms for the species A. fecundator are A. fecundatrix, A. pilosus, A. foecundatrix, A. gemmarum, A. gemmae, A. gemmaequercus, A. gemmaecinaraeformis and A. quercusgemmae.
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.
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.
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.
Cynipinae is a subfamily of gall wasps (Cynipidae). Many of the approximately 1,500 described species cause galls on oaks, but some induce galls on other plant species or are inquilines of the gall-inducing species. Species occur on all continents except Antarctica, with most found in the temperate regions of the northern hemisphere. All extant cynipid species are within Cynipinae since the only other recognized subfamily is Hodiernocynipinae which is based on the fossil genus Hodiernocynips.
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 quercuscalifornicus, or the California gall wasp, is a small wasp species that induces oak apple galls on white oaks, primarily the valley oak but also other species such as Quercus berberidifolia. The California gall wasp is considered an ecosystem engineer, capable of manipulating the growth of galls for their own development. It is found from Washington, Oregon, and California to northern regions of Mexico. Often multiple wasps in different life stages occupy the same gall. The induced galls help establish complex insect communities, promoting the diversification in niche differentiation. Furthermore, the adaptive value of these galls could be attributed their ecological benefits such as nutrition, provision of microenvironment, and enemy avoidance.
Cynips quercusechinus, the urchin gall wasp, is a species of gall wasp in the family Cynipidae. It induces galls in the leaves and leaf buds of blue oak and scrub oak. Like other oak gall wasps, it has two generations: a bisexual generation, and a parthenogenic female generation. In spring, the hatching bisexual generation produces hollow green galls in leaf buds. In summer, the unisexual generation induces its galls, which are red or pink and resemble sea urchins, on the undersides of leaves. These galls are about 10 millimetres (0.39 in) in diameter. The galls fall with the leaves in autumn, and the larvae inside of them emerge as adults in the spring and lay their eggs.
Acraspis quercushirta, the jewel oak gall wasp, is a species of gall wasp in the family Cynipidae, tribe Cynipini, found in North America.
Druon ignotum is a species of gall wasp in the family Cynipidae.
Burnettweldia is a genus of oak gall wasps in the Nearctic.
Andricus parmula, also known as the disc gall wasp, is a species of gall-forming wasp in the genus Andricus. It induces galls in a wide selection of oak species, especially white oaks, and including hybrids. The galls are disc-shaped, up to 3 mm in diameter, and pale with red streaking. Adult females emerge in April. The galls induced by A. parmula superficially resemble the galls of Andricus gigas,Andricus viscidus, and newly identified species called the "plate gall wasp" and the "orange-cap gall wasp" by Richard Russo. Galls induced by this wasp have been documented in Oregon and California on the Pacific coast of North America.
Burnettweldia plumbella, also known as the beaked twig gall wasp, is a species of gall wasp. Previously in the genus Disholcaspis, it was moved into a new genus, Burnettweldia, in 2021. This wasp induces galls on oak trees, including blue oak, leather oak, Muller's oak, and scrub oaks. The galls are up to 15 mm in diameter and brightly colored, coming in either red with yellow spots or green with yellow spots. Their name comes from the galls' pointed tip. Galls are formed in spring and summer, and adults emerge from them in November and December. The adult wasps are 3–4 mm in length.
Acraspis guadaloupensis is a relatively uncommon species of cynipid wasp that produces galls on intermediate oaks. The intermediate oak disc wasp was first described in 1911 and has been moved between genera more than once. Distribution is limited to California in North America. The flattened galls appear on leaves of Quercus chrysolepis, the canyon live oak.
Atrusca bella, also known as the little oak-apple gall wasp, is a locally common species of cynipid wasp that produces galls on oak trees in North America. The wasp oviposits on Arizona white oak, Mexican blue oak, netleaf oak, Toumey oak, and shrub live oak. The larval chamber is at the center of the gall, connected to the husk by slender, radiating fibers. The gall induced by this wasp is larger, lighter-colored, and more common than the similar gall induced by Atrusca brevipennata. This wasp has been observed in Arizona and New Mexico.
Besbicus heldae, formerly Cynips heldae, also known as the thorny gall wasp or thorn gall wasp, is an uncommon species of cynipid wasp that induces bud galls on Oregon oak and valley oak trees on the west coast of North America. Fresh gall are rose pink, measure 6–16 mm in diameter, and have a "mealy-granular" surface and possibly overlapping, disorderly looking "spikes". Galls are detachable and turn brown as they age. This gall superficially resembles the galls induced by Burnettweldia corallina or Cynips quercusechinus.
