Knopper Oak Gall Wasp - Andricus quercuscalicis

A Cynipid  gall wasp that causes common and familiar Knopper galls to form on the acorns of various oaks. The gall is seen more often than the adult wasp.

The knoppers are the agamic (asexual) galls, and are a mass of ridged tissue with a large central cavity and small inner gall. 

The sexual galls are found in Turkey oak catkins, and are small (1.5mm - 2mm) and rounded/cone-shaped; green at first and then brown.  They are common but rarely recorded

Andricus grossulariae has similar asexual galls on oak acorn cups and forms much larger, red sexual galls in Turkey Oak catkins

Agamic gall Sexual gall Adult

Native and Turkey oaks

May to July.

A recent introduction to the British Isles, first arriving in the 1960s and now found throughout England, Wales and as far north as Scotland.

Common in Leicestershire and Rutland.