''Andricus curvator'' is a

gall wasp 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 generall ...

which forms chemically induced leaf

gall 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 ...

s on

oak trees 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 ...

and has both

agamic Religion *Āgama (Buddhism), a collection of Early Buddhist texts *Āgama (Hinduism), scriptures of several Hindu sects *Jain literature (Jain Āgamas), various canonical scriptures in Jainism Other uses * ''Agama'' (lizard), a genus of lizards ...

and sexual generations. Agamic and sexual generations usually form two distinct galls on oak trees, but in the case of ''A. curvator'' there are six galls; the sexual generation usually on the leaf, occasionally in a twig or catkin, and the agamic generation in a bud. The wasp was first described by

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 Humboldt University of Berlin, Berlin (1824–1827), and was successively lecturer and pr ...

, a German biologist, in 1840 and is found in most of Europe.

Life cycle

Adult gall wasps emerge in the spring, from galls formed on the bud the previous year. The spring generation lay eggs usually on a leaf, occasionally on a twig or on catkins and the leaf galls appear soon after the leaves emerge. They are approximately 8 mm, roughly globular and have thin walls with a small inner gall. They often coalesce and can clustered near the leaf base where they can cause distortion. Galls on a twig cause the twig to bend and it can also occur at the tip. These galls have an interior cavity which can be spherical or oval. A fourth sexual gall can also develop on the base of a catkin stalk and is up to 5 mm diameter. What remains of the catkin is bent 90° and can still be seen at the tip. The female wasp develop within the gall and emerge in May or June, laying her eggs on a young bud. Sometimes known as a collared gall the asexual gall is often concealed among the bud scales, and at first, are difficult to find. The scales may fall away, exposing a 3 mm, smooth, brown, skittle-shaped gall with a nipple-like tip, usually surrounded by a pale ring. In old galls the ring may not be seen. The wasp overwinters in the gall. The galls have been found on Algerian oak (''

Quercus canariensis ''Quercus canariensis'', the Algerian oak, Mirbeck's oak or zean oak, is an oak in the section ''Quercus'' sect. ''Mesobalanus'', native to southern Portugal, Spain, Tunisia, Algeria and Morocco. Despite the scientific name, it does not occur na ...

''), Turkey oak (''

Quercus cerris ''Quercus cerris'', the Turkey oak or Austrian oak, is an oak native to south-eastern Europe and Asia Minor. It is the type species of ''Quercus'' sect. ''Cerris'', a section of the genus characterised by shoot buds surrounded by soft bristles, ...

''), Portuguese oak (''

Quercus faginea ''Quercus faginea'', the Portuguese oak, is a species of oak native to the western Mediterranean region in the Iberian Peninsula. Similar trees in the Atlas Mountains of northwest Africa are usually included in this species, or sometimes treate ...

''), Spanish oak ('' Quercus × hispanica''), 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 ...

''), Pyrenean oak (''

Quercus pyrenaica ''Quercus pyrenaica'', commonly known as Pyrenean oak, is a tree native to southwestern Europe and northwestern North Africa. Despite its common name, it is rarely found in the Pyrenees Mountains and is more abundant in northern Portugal and nort ...

'') and 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 plant, native to most of Europe west of the Caucasus ...

'').

Distribution

The gall is found 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 inv ...

and from

Fennoscandia __NOTOC__ Fennoscandia (Finnish language, Finnish, Swedish language, Swedish and no, Fennoskandia, nocat=1; russian: Фенноскандия, Fennoskandiya) or the Fennoscandian Peninsula is the geographical peninsula in Europe, which includes ...

to the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...

References

External links

{{Taxonbar, from=Q14409594 Cynipidae Gall-inducing insects Hymenoptera of Europe Insects described in 1840 Oak galls Taxa named by Theodor Hartig