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.
The specific identity of the species of Euura in this study is uncertain.
This particular species of Euura produces stem galls on crack willow, S. fragilis L. Apparently, this species of willow was originally planted from nursery stock and has become established along drainages in the Front Range of Colorado (Harrington, 1954).
Gall development occurred rapidly. By the end of May gall diameter reached 7.1 mm (Fig. 1). However, average gall size varied greatly throughout the season, ranging from a diameter of 5.8 mm (wet weight 0.22 g) to 10.5 mm (wet weight 3.3 g) (Fig. 2).