Euura breweriae, n. sp.

[Photos of many examples of this gall appear in Figure 34, page 16 of the pdf]

GALL.—Lasiolepoid-type (Fig. 34); thin walled, elongate, irregular in shape, 20-40 mm long X 5-15 mm wide; color vivid yellow-green tinged with red; immature galls very pubescent, pale green; mature galls shiny; 1-3 larvae/gall.

Host.—Salix breweri Bebb.

Range.—Inner California Coast Ranges presumably with the willow, 50-300 m; sawfly collected only from Putah Creek basin, southwest Yolo and adjacent Napa Counties, 50-75 km west of Sacramento.

Remarks. — Emergence and oviposition April to early May. The host range is poorly known; S. breweri is a clustering serpentine endemic within stream beds in the Chaparral of the inner California coast ranges, 0.5-3 m tall, the dominant willow along the main tributaries of the upper Putah Creek basin.

Euura breweriae
Brewer's-stem-gall sawfly
[Page 213]

This sawfly induces linear, lopsided, integral, polythalamous stem galls on Brewer's willow (Salix breweri).