The gall's range is computed from the range of all hosts that the gall occurs on. In some cases we have evidence that the gall does not occur across the full range of the hosts and we will remove these places from the range. For undescribed species we will show the expected range based on hosts plus where the galls have been observed.
Gall. (Plate XXIV, Figs. 1-8.) On the stalks of wild lettuce (Lactuca canadensis), usually near the summit and often in the panicle, and then covered with short flower stalks. Polythalamous. More or less rounded or elongate irregular swellings of various shapes. Green when fresh and brown when old and dry. Inside (Fig. 8) the gall is pithy and contains numerous larval cells: Length, 25-75 mm.
Habitat: Canada; New England and Middle States, southward and westward.
