Euura scoulerianae, n. sp.

[Photos of many examples of this gall appear in Figure 33, page 16 of the pdf]

GALL. — Exiguoid-type (Fig. 33); thick walled, shape elongate, irregular, usually tapering apically, 20-40 mm long X 5-15 mm wide, surface smooth, occasionally pubescent, but usually shiny; young gall dark green with red mottlings which usually turn brown on mature galls; exit hole cut by mature larva and plugged with frass before pupating; gall often dried hard and colored gray by spring; host willow a clustering shrub or small tree, usually under 4 m, with pungent foliage, even when dried; willow usually on very dry elevations (for a willow) in yellow pine-red fir and lodgepole pine forests.

Host.—Salix scouleriana Barratt.

Range.—With the willow in the Sierra Nevada and adjacent ranges from Mt. Shasta southward, between 1300 and 2100 m.

Remarks.—Emergence and oviposition from early May to mid June, with cocooning in late September. This is a sympatric sibling species with E. lemmoniae and E. lasiolepis. The scarcity of paratypes results from late recognition of the species (1967) and the consistently high level of parasitism (rarely below 75%) throughout its range.

Euura scoulerianae
Scouler's stem-gall sawfly
[Page 215]

This sawfly induces thick-walled, elongate, smooth, integral stem galls on Scouler's willow (Salix scouleriana).