180 PROCEEDINGS OF THE 



"broad as long, with medial constriction scarcely perceptible. 

 Thorax reddish orange, with three dorsal blackish fuscous stripes 

 which have in certain lights a whitish appearance, the side stripes 

 extend to scutellum ; between these stripes, seated on a somewhat 

 dusky ground, are two rows of dark hairs, shining white in 

 certain aspects, and outside the stripes are two more similar rows, 

 four altogether ; scutellum yellow; breast greyish fuscous; halteres 

 pale yellow or very pale yellowish white, club dusky at base, and 

 in certain aspects glistening white. Abdomen orange-red or flesh- 

 red, paler beneath, with the usual broad dorsal black bands of 

 scale-hairs, and the hind margins of segments above with scattered 

 fringe of long, partly black hairs, especially the two apical 

 segments ; ovipositor long, pale ochreous yellow, basal joint 

 greyish fuscous at base above, no lamellae. Legs proportionately 

 short and stout, fuscous, paler beneath, and somewhat shining 

 white. Wings dark grey (roots yellow), iridescent ; costa deep 

 fuscous, first and second longitudinal nervures paler fuscous, third 

 very pale ; second longitudinal nervure curves slightly upwards at 

 the transverse nervure, and slightly convex to hind margin at the 

 middle, proceeds thence straight to margin, which it joins before 

 apex of wing ; third longitudinal nervure has the stem straight, 

 the lower branch of fork is a continuation of the stem, proceeding 

 with a moderately sharp but gradual curve downwards to margin, 

 which it joins at an oblique angle, the upper branch leaves at a 

 sharp angle with immediately another abrupt bend in the opposite 

 direction, and thence proceeds straight to margin. 



Length (ovipositor retracted), half a line. 



The male also has the antennae 12-jointed, joints sessile. I 

 succeeded in rearing only a single example amongst the large 

 number of females. 



After death all the yellowish parts of thorax and abdomen 

 assume, more or less, a fuscous tinge, and the dorsal stripes of 

 thorax become undistinguishable ; scutellum and halteres become 

 dusky yellow, and basal joint of ovipositor changes to dark 

 fuscous ; the remaining joints are a little more ochreous than 

 in life. 



The 12 sessile joints of the antennae in both sexes, and the 

 thoracic stripes, distinguish tins species readily from its allies. 

 G. saliceti, ^Yinn., wliich produces similar deformations on the 

 willow, is larger, and differs in colour and in the antennae. 



