Cola-nut gallsDarlington, 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

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.

References

External links

* * {{Taxonbar, from=Q4759306 Cynipidae Gall-inducing insects Hymenoptera of Asia Hymenoptera of Europe Insects described in 1840 Oak galls Taxa named by Theodor Hartig

The physical appearance of the galls

Distribution

Life-cycle

See also

References

External links