The study of plant galls and the keys to their identification have an almost century-long tradition in the Netherlands, culminating in several revised editions of Docters van Leeuwen’s “Gallenboek” by the first author. For Belgium and Luxembourg, Jacques Lambinon substantially contributed with his “Aide-mémoire de cécidologie”, which was later revised and enhanced by the second author.

The recent publication by the first author of “Plant Galls of Europe” also made a new advan...