Larvae cause the growth of soft, variably shaped galls in newly developing stems [, compressing] the stem nodes ... [C]lump[ed] foliage just above [may] includ[e] leaves that form a sheath around the gall. Later the stem extends beyond this rosette ... By mid- to late March many galls have reached full size (12-20mm long x 10-l2mm diameter) [and] are whitish or pale green with fleshy walls 2-5mm thick ... [L]arvae reach maturity in April, when each cuts a hole in the gall and drops to the ground ... By ... early to rnid-April, [the galls] are white tinged with purplish brown exteriorly. Later, the remaining gall tissue deteriorates [leaving a] clustering of nodes and twigs ...

[for monochrome photo of gall, see pg. 45]