The plant is injured by the insect working during the larval stage in the terminal buds of spurs and branches, causing the bud to become abnormal both in size and structure. The bud scales increase greatly in numbers and size and, lying closely one upon another form a gall somewhat resembling in miniature the pine-cone willow galls so commonly encountered upon the tips of willow twigs. The injured bud is incapable of producing normal leaves and the plant, striving to maintain itself, develops secondary buds within or about the first and these, in turn, becoming infested, there is formed ultimately a large knot or cluster of galls. A typical cluster is illustrated in figure 1. Occasionally the injured cluster succeeds in putting out feeble growths which usually take the form of undersized twigs. Such a cluster, starting to develop, may be seen in figure 2. These growths appear at the end of the_first or second season as illustrated by figure 3. As a rule, however, this secondary-, "witch-broom" like growth does not develop, and one finds the infested plant with numerous, large, rounded gall-clusters located on any part of it as shown by figure 4.

- JS Houser: (1911) The Gooseberry Gall Midge or Bud Deformer^©