Cola-nut galls
[Darlington, Arnold (1975) ''The Pocket Encyclopaedia of Plant Galls in Colour.'' Pub. Blandford Press. Poole. . P. 155.] develop as a chemically induced distortion of leaf axillary or terminal buds on
pedunculate oak
''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 widel ...
(''Quercus robur'') or
sessile oak
''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 embl ...
(''Quercus petraea'') trees, caused by the agamic
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 ...
''Andricus lignicola'' (
Hartig, 1840) which lays single eggs within leaf buds using their
ovipositor
The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...
. A previous name or synonym for the species ''A. lignicola'' is ''A. lignicolus'' and ''A. venheurni''.
The physical appearance of the galls
The galls are found in small groups, which however do not coalesce, helping to prevent mis-identification with the
oak marble gall
''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'' ...
(''Andricus kollari''), in addition the shape is ovoid rather than spherical and it is scaly rather than smooth. It grows up to about 10 x 8 mm and is at first green, rapidly changing to grey-brown, with light red patches where the original bud scales have separated. It is hard and firm, but does not always persist on the tree for very long.
[Stubbs, F. B. Edit. (1986) ''Provisional Keys to British Plant Galls''. Pub. Brit Plant Gall Soc. . P. 52.] Once the imago has emerged a small circular hole is apparent.
Distribution
![Andricus lignicola - the Cola-nut gall](https://upload.wikimedia.org/wikipedia/commons/7/70/Andricus_lignicola_-_the_Cola-nut_gall.JPG)
It is well known in continental Europe, occurring from Great Britain to Asia Minor.
Life-cycle
The
imago
In biology, the imago (Latin for "image") is the last stage an insect attains during its metamorphosis, its process of growth and development; it is also called the imaginal stage, the stage in which the insect attains maturity. It follows the f ...
of the agamic phase emerges in early summer following the gall's inception. The bisexual generation gall is very similar to that of ''A. kollari,'' effecting the live bud of ''Quercus'' species
and has only been seen under culture conditions (1975).
[Darlington, Arnold (1975) ''The Pocket Encyclopaedia of Plant Galls in Colour.'' Pub. Blandford Press. Poole. . p. 155.] Removing and destroying cola-nut galls before they dry and the wasps emerge may help to reduce an infestation. While fairly large, and sometimes present in quite large numbers on scrub specimens, they cause no measurable harm.
See also
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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 ...
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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 ...
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Knopper gall
''Andricus quercuscalicis'' is a gall wasp species inducing knopper galls.
Knopper galls develop as a chemically induced distortion of growing acorns on pedunculate oak (''Quercus robur'' L.) trees, caused by gall wasps, which lay eggs in buds w ...
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Oak apple
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 in diameter and are caused by chemicals injected by the larva of certain kinds of gall ...
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Oak marble gall
''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'' ...
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Pineapple gall
The Pineapple gall adelgid (''Adelges abietis'') is a type of conifer-feeding insect that forms pineapple-shaped plant galls on its host species, commonly Norway and Sitka spruce. The adelgids (genus ''Adelges'') are pear-shaped, soft-bodied gr ...
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Red-pea gall
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 ...
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Rose bedeguar gall
''Diplolepis rosae'' is a gall wasp which causes a gall known as the rose bedeguar gall, Robin's pincushion, mossy rose gall, or simply moss gall.Darlington, Arnold (1975) ''The Pocket Encyclopaedia of Plant Galls in Colour.'' Pub. Blandford Pres ...
References
External links
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{{Taxonbar, from=Q4759306
Cynipidae
Gall-inducing insects
Hymenoptera of Asia
Hymenoptera of Europe
Insects described in 1840
Oak galls
Taxa named by Theodor Hartig