Marble Gall

Andricus kollari

Marble Galls on English Oak are formed by the asexual generation of the Gall wasp Andricus kollari on leaf buds. Each gall, which can grow up to 25mm in diameter, contains a single larva. The galls start off green and change to brown in the autumn. They are rich in tannin and may have been brought to Britain in the 19th century as a source of tannin for the ink-making and dyeing industries. Typically, there is one prominent opening through which newly developed adults emerge after transitioning from the larval stage. Smaller openings are often created by inquiline insects that utilize the living space of other organisms. Also found on Sessile Oak.