246 THE CANADIAN ENTOMOLOGIST. 

 « 



Pupa.— Much, like the mature insect, but with rudimentary wings. 

 All brownish-yellow, the legs, cases and antennae darker, eyes blackish. 



The flies emerged in August. 

 Crcesus latitarsus, Norton. 



(The white birch saw-fly.) 



Eggs. — Laid closely along the midrib or larger veins on the under 

 side of the leaf, about half enclosed in median saw-cuts which are dis- 

 tended by the eggs so that they lie obliquely in contact. Soft, translucent 

 white ; seen to be very minutely punctured under a magnification of 60 

 diameters. Size, 1.4X.6 mm. 



First stage. — Eating holes through the leaf, which soon become con- 

 fluent ; lashing the body. Head round, a little higher than wide, full at 

 vertex; shining black; width, 0.4 mm. Body light shining greenish. 

 Tubercles very obscure, not setiferous, only the subventral ones distinct 

 and nearly concolorous. Thoracic feet blackish ; the segments of body 

 obscurely annulate. 



Second stage. — Head very smooth, even brownish-black, pale above 

 the mouth ;* width, 0.55 mm. Body olive-green, the subventral ridge 

 and feet blackish. No setae seen. 



Third stage. — Head black; width, 0.75 mm. Much the same. 



Fourth stage. — Head, 1.05 mm. wide. Markings much as before. 



Fifth stage. — Head round, full at vertex, well rounded, not pointed, 

 without trace of sutures ; flattened in front over clypeus, with a few slight 

 clypeal dents. Entirely shining black ; width, 1.6 mm. Body indistinctly 

 4-annulate, watery shining smooth; no dots, but minute black setae 

 represent them. Thoracic feet large, spreading, black, pale centrally. 

 Abdominal feet present on joints 6-1 1 and 13 (20 feet), with a medio- 

 ventral eversible gland, posterior to each pair on joints 6-10. These 

 glands are longer than the feet, when everted, are coloured rather darker 

 than the body. When disturbed the larva throws its body up over its 

 head and the ventral glands are quickly everted and retracted. Ground 

 colour honey-yellow heavily shaded with greenish black, the yellow 

 appearing on joint 2 anteriorly, stigmatally and on the abdominal feet. 



Sixth stage. — Width of head, 2. 2 mm. As before, but smooth ; no 

 setae seen. Joint 2, the dorsal and stigmatal irregular bands and abdom- 

 inal feet honey-yellow, leaving the black shading most distinct subdorsally 



