Andricus quercuscalicis
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Andricus quercuscalicis is a gall wasp species inducing knopper galls.
Galls (upper left and right) formed on acorns on the branch of a pedunculate (or English) oak tree by the parthenogenetic generation Andricus quercuscalicis.
A larva of Andricus quercuscalicis in a gall formed in Quercus robur
Oak apple
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An oak apple or oak gall is a large, round, vaguely apple-like gall commonly found on many species of oak. Oak apples range in size from 2 to 4 centimetres in diameter and are caused by chemicals inje
Oak apples on Quercus robur leaf
Oak galls on a Pyrenean oak (Quercus pyrenaica) in León, Spain.
An oak apple on a tree in Worcestershire, England
An oak apple on an oak leaf.