Oak apple or oak gall is the common name for a large, round, vaguely apple-like gall commonly found on many species of oak. Oak apples range in size from 2 to 4 centimetres in diameter and are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae. The adult female wasp lays single eggs in developing leaf buds. The wasp larvae feed on the gall tissue resulting from their secretions, which modify the oak bud into the gall, a structure that protects the developing larvae until they undergo metamorphosis into adults. Considerable confusion exists in the general "literature" between the oak apple and the oak marble gall. The oak marble is frequently called the oak apple due to the superficial resemblance and the preponderance of the oak marble gall in the wild. Other galls found on oak trees include the oak artichoke gall and the acorn cup gall, but each of these has its own distinctive form.
Dryocosmus are a genus of gall wasps. They are cyclically parthenogenetic insects that induce galls on plants in the family Fagaceae.
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 is a genus of gall wasps in the family Cynipidae, comprising the following species:
Biorhiza pallida is a gall wasp species in the family Cynipidae. This species is a member of the tribe Cynipini: the oak gall wasp tribe. Cynipini is the tribe partially responsible for the formation of galls known as oak apples on oak trees. These are formed after the wasp lays eggs inside the leaf buds and the plant tissues swell as the larvae of the gall wasp develop inside. This wasp has a widespread distribution within Europe.
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.
Barucynips is a genus of gall wasp consisting of a single species also described by Medianero and Nieves-Aldrey in 2013: Barucynips panamensis.
Coffeikokkos is a genus of gall wasp.
Dryocosmus jungalii is a gall wasp species in the family Cynipidae whose life cycle involves only Palaearctic oaks, Quercus subgen. Quercus, in the section Cerris.
Trichagalma formosana is a gall wasp species in the family Cynipidae whose life cycle involves only Palaearctic oaks, Quercus subgen. Quercus, in the section Cerris. It is endemic to Taiwan.
Aphelonyx kordestanica is a gall wasp species in the family Cynipidae whose life cycle involves only Palaearctic oaks, Quercus subgen. Quercus, in the section Cerris.
Aphelonyx is a genus of gall wasps in the family Cynipidae, comprising three known species:
Atrusca is a genus of gall wasps in the family Cynipidae. It consists of approximately 50 species, and is found in North and Central America.
Bassettia is a genus of gall wasps found in North America.
Bassettia pallida is a species of gall wasp found in the Southern United States. This species was described by American entomologist William Harris Ashmead in 1896. B. pallida reproduces asexually in galls it induces on oak trees. The parasite Euderus set, a chalcid wasp, has B. pallida as a host and manipulates its behavior.
Amphibolips is an American genus of gall wasps in the family Cynipidae. There are about 52 described species in Amphibolips.
Heteroecus is a genus of gall wasps in the family Cynipidae. There are about seven described species in Heteroecus.
Belonocnema is a genus of gall wasps in the family Cynipidae. There are at least four described species in Belonocnema.
Disholcaspis is a genus of gall wasps in the family Cynipidae. There are more than 20 described species in Disholcaspis.
Callirhytis is a genus of gall wasps in the family Cynipidae. There are more than 90 described species in Callirhytis.
