''Andricus inflator'' is a species of gall-forming wasps, in the genus ''

Andricus ''Andricus'' is a genus of oak gall wasps in the family Cynipidae. Life cycle As in all Hymenoptera, sex-determination in species of the genus ''Andricus'' is governed by haplodiploidy: males develop from unfertilized eggs and are haploid, ...

'', which has a sexual and an asexual generation, producing two different

galls Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) 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 be ...

. The wasp was named by the German biologist

Theodor Hartig Theodor Hartig (21 February 1805 – 26 March 1880) was a German forestry biologist and botanist. Biography Hartig was born in Dillenburg. He was educated in Berlin (1824–1827), and was successively lecturer and professor of forestry at the Univ ...

, in 1840 and is found in Europe.

Description of the gall

Like many oak gall wasps, there are two generations per cycle, with one sexual and one asexual, each creating different galls. In spring, the sexual gall is a swelling at the tip of the twig which can be up to 15 mm across. The interior cavitity is long and narrow and at the bottom is an egg-shaped inner gall, containing the larval gall wasp. Old galls persist and can have new shoots growing from them. They are green at first, later becoming the same colour as the twig. The wasps emerge in the summer and after mating, females from the sexual gall lay their eggs on a bud, especially on buds sprouting straight from the trunk. The resulting asexual gall is a small, green, egg-shaped swelling up to 6 mm across and is surrounded by bud scales. Each gall contains a single larva {according to Chinery) or more (according to Plant Parasites of Europe), can be found from September to November and, as it matures, turns brown, falling to the ground in late autumn. Larvae pupate in the gall and appear in the spring although some can spend two or three winters in the gall before they emerge to lay eggs in the young twigs. Female wasps lay their eggs on various species of

oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

, including Hungarian oak (''

Quercus frainetto ''Quercus frainetto'' (syn. ''Quercus conferta'' Kit., ''Quercus farnetto'' Ten.), commonly known as the Hungarian oak or Italian oak, is a species of oak, native to southeastern Europe (parts of Italy, the Balkans, parts of Hungary, Romania) an ...

''), Lusitanian oak (''

Quercus lusitanica ''Quercus lusitanica'', commonly known as gall oak, Lusitanian oak, or dyer's oak, is a species of oak native to Portugal, Spain (Galicia and western Andalucia) and Morocco. ''Quercus lusitanica'' is the source of commercial nutgalls. These galls ...

''), sessile oak (''

Quercus petraea ''Quercus petraea'', commonly known as the sessile oak, Cornish oak, Irish Oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emble ...

''), downy oak (''

Quercus pubescens ''Quercus pubescens'', the downy oak or pubescent oak, is a species of white oak (genus ''Quercus'' sect. ''Quercus'') native to southern Europe and southwest Asia, from northern Spain (Pyrenees) east to the Crimea and the Caucasus. It is also fou ...

''), pedunculate oak ''(

Quercus robur ''Quercus robur'', commonly known as common oak, pedunculate oak, European oak or English oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native to most of Europe west of the Caucasus. It is wid ...

'') and northern red oak (''

Quercus rubra ''Quercus rubra'', the northern red oak, is an oak tree in the red oak group (''Quercus'' section ''Lobatae''). It is a native of North America, in the eastern and central United States and southeast and south-central Canada. It has been intro ...

''). ;Similar species * At the tip of a twig the swelling of ''

Andricus curvator ''Andricus curvator'' is a gall wasp which forms chemically induced leaf galls on oak trees and has both agamic and sexual generations. Agamic and sexual generations usually form two distinct galls on oak trees, but in the case of ''A. curvator'' ...

'' has an interior cavity that is spherical or oval, compared with the sexual gall of ''A. inflator'' where the interior is long and narrow. * '' Andricus quercusramuli'' is egg-shaped, smaller than the asexual gall of '' A. inflator'', up to 3.5 mm long and also matures in the autumn. * '' Andricus infectorius'' asexual gall is similar with a 10–20 mm swelling when mature in October, falling from the tree during the winter. The colour varies from green to dark brown as it matures.

Distribution

The wasp is found in Europe from

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

to the

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian invas ...

References

{{Taxonbar, from=Q14581826 Cynipidae Gall-inducing insects Hymenoptera of Europe Insects described in 1840 Oak galls Taxa named by Theodor Hartig