Saw-fiies 7 g 



mesosternum, and the metapleura smooth, the former setaceous and the two 

 latter polished; the wings hyaline, the veins brownish, the stigma pale, the free 

 part of R^ and M'' interstitial or nearly so; the claws long and slender, deeply 

 cleft, the inner ray two-thirds the length of the outer; the saw-guides broad, 

 the proximal part, of the ventral margin straight and the distral portion rounded 

 to the concave dorsal margin, not tapering, distal end subtruncate, the surface 

 sparsely setaceous; the cerci short and slender, extending to the middle of 

 the saw-guides; colour black, the legs beyond the knees whitish. Length, 5 

 mm. 



Male.— The male differs from the female in that the mpdian fovea is 

 deeper and more distinctly punctiform, the furrow interrupting the frontal 

 crest is deeper and broader, the ocellar basin is concave but the frontal ridges 

 are wanting, the dorsal half of the head is more coarsely granular than the 

 ventral portion, the vertical furrows are longer and broader and connected 

 with a broad depression representing the ocellar basin, the antennae are longer 

 but are stout and segments three and four are subequal; the procidentia are 

 short bluntly rounded projections. Length, 5 mm. 



Larva. — Body white, head variable in colour, usually darker than the 

 remainder of the body; ocularia typical in form and size, the ocellus placed 

 in the center; the antennae convex oval areas bounded by a brownish line, 

 located ventro-mesad of the ocularia, and its surface bearing about six minute 

 chitinized areas; head usually darker in colour dorsad of a line drawn through 

 the ocularia, sometimes with a spot on the dorsal half of the front and a curved 

 fuscous band connecting the ocularia, the darker colour due in part to the number 

 and intensity of the minute round or oval areas of which they are composed; 

 mandibles distinctly dentate; spinneret large and prominent; microthorax 

 linear, fuscous in colour; prothorax with three annulets, the second much larger 

 than the others and interrupted on the meson and each lateral portion swollen, 

 also each lateral. portion of the first annulet; the spiracular area oval, swollen, 

 and transverse, with five to eight setae; pedal area small with two or three 

 setae; mesothorax and metathorax with four sparsely setaceous annulets, the 

 first short and greatly swollen, the second and third subsequal in length and 

 swollen except the mesal portion of the second, the fourth small, the spiracular 

 area large and swollen, the pedal areas similar to those of the prothorax; 

 abdominal segments one to eight with four annulets, the first more swollen than 

 the fourth, the second and third more swollen than the first, the second with a 

 lighter coloured mesal portion usually bearing a single seta on each side of the 

 meson, annulets with transverse rows of setae; the spiracular, postspiracular, 

 and pedal areas large and swollen and setaceous; tergum of the tenth segment 

 with small round black spots ; prolegs long and blunt, cephalic and mesal portions 

 setaceous; legs with strongly chitinized portions brownish. Length 10-12 mm. 



Galls. — Galls usually located near the midrib and projecting about equally 

 onto both surfaces of the leaf, about the size of a large pea or slightly larger, the 

 surface w^th depressions with irregular swellings between, in some specimens 

 one-half of the gall bluntly pointed; colour probably brownish or reddish, a 

 single gall on a leaf. Galls formed on leaves of creeping willow Salix arctica. 



Breeding Record 35. "Host-plant Salix arctica. Galls. Several imagines 

 reared. It was noted during the rearing that the emerging imagines were of 

 different sizes (6 or 7 mm.) ; so that they may well have been of different species." 



Herschel island, Yukon Territory. Larvae collected August 13, 1914. 

 Imagines emerged July, 1915. F. Johansen, collector. Female No. 264; 

 males Nos. 254, 257, 259, 261, 263, and 266. 



This species is related to kincaidi Marlatt, from which it can be separ- 

 ated by the shape of the median fovea, the deep interruption of the frontal 

 crest, the form of the claws, and the colour. 



