[The galls] are found commonly on a main stem, but rarely on a branch. The flower cluster is sometimes entirely aborted, but usually only partly so, the lower pedicels in the cluster remaining normal.
In the majority of cases the gall is terminal, but in a few instances the stem ... project[s] a short distance beyond it. The gall has the relatively simple structure of a spindle-shaped enlargement of the stem. In length it varies from 10 to 15 mm, and in greatest width from 5 to 8 mm.
It is roughened on the outside by the stumps of the aborted branches. On account of the shortening of the stem axis and the consequent crowding of the nodes, these branches are more numerous on a gall than on a corresponding length of normal stem. This gives the gall a gnarled surface and forms a strongly-protected case for the larva. The gall in some cases is surmounted by a tuft of leaves growing from its apex.
The aperture through which the moth escapes from the gall is made always near the upper end.
The insect passes the winter in the larval condition.

- A. Cosens: (1908) A NEW LEPIDOPTEROUS GALL-PRODUCER^©