The bud of the host species is about twice the normalsize and pear-shape. The greenish larva feeds within the gall which also contains frass and the bud falls to the ground in the autumn where the larva pupates. Several buds on the same shoot can be galled and the insect has a single generation per year. Most species of Euura are monophagous on Salix species but there is some discussion on whetherEuura mucronata is a group of closely related species, each feeding on different Salix species, or whether it is polyphagous feeding on over thirtyspecies of willow.