Cornish Biodiversity Network  -  Supporting Wildlife Recording

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Cornish Red Data (2009)

The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.

Andricus quercusramuli - Cotton Wool Gall

Range & Status

Hymenoptera: Cynipidae; both sexual (on catkins) and agamic (on buds) stages are uncommon.

Regional Distribution

Both stages were recorded in Cornwall pre-1906. In 1989 the sexual stage was recorded on the south bank of the River Camel Trail SW97.

Habitat & Ecology

Associated species: Quercus spp. Galls on catkins (sexual) cause a mass of white cotton wool-like hairs up to 20 mm. long completely concealing the gall chambers; up to 20 chambers, each with a larva.


Oak trees have been affected and died in recent years; this may have been caused by drought brought on by possible global warming and/or the spread of Sudden Oak Death disease, Phytophthora ramorum . The decline of oak trees will cause a major negative environmental effect on all invertebrate species which depend on Quercus , not just those that form galls.


Foresters are planting Quercus robur , but more research on causes of oak deaths and into disease resistant species of oak should be conducted.


I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.

The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.