Euura lasiolepis n. sp.

[Photos of many examples of this gall appear in Figure 35, page 16 of the pdf]

GALL.—Lasiolepoid-type (Fig. 35); thick walled, tortuous; surface smooth, shiny, or corrugated; color yellow-green except purple to red in bright sun; 20-70 mm long X 3-21 mm wide; 1-5 larvae/gall; willow a shrub or small tree usually under 5 m, but to 10 m in wet sites.

Host.—Salix lasiolepis Bentham.

Range.—With the willow at least from Monterey County north to Mendocino County, California, and from the coast to the west face of the Sierra Nevada (but see subsequent discussion).

Remarks.—Emergence and oviposition from late February to early June, peaking in early March; coast and valley populations with cocooning from October through February. Locally very abundant on susceptible willow clones along roadside ditches and sloughs, and marshy areas along foothill streams. East of the Sierra Nevada Divide from 1225—1825 m is a black Euura on S. lasiolepis, average saw L:W = 17.5:1, dimensions 1.56 mm X 0.09 mm, body slightly paler and smaller than coastal (black) phase. For status of this, another form on 3". rigida, and sibling species on S. scouleriana, see discussion of speciation in stem-galling Euura.

Euura lasiolepis Smith

The stem galling sawfly, Euura lasiolepis Smith, hereafter called the stem galler, oviposits in the petioles of very young leaves and initiates a gall in the stem below the leaf. The mature gall is a greatly swollen portion of the new shoot (Price and Craig 1984). Larvae feed in tissue derived from the pith in the developing stem (Smith 1970). The stem galler overwinters and then pupates in its gall.

Range: along streams and near springs from 1200-2400 m in northern Arizona

Euura lasiolepis
Stem-gall sawfly
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This sawfly induces thick-walled, lopsided, integral stem galls on arroyo willow (Salix lasiolepis).