210 THE CANADIAN ENTOMOLOGIST. 



fied at the extremities. Spiracles black. At the end of this stage the 

 larvae empty their intestinal canals and spin cocoons on the surface of the 

 ground without moulting. 



Cocooti entirely of yellow silk, double, the outer layer of coarse 

 meshes, the inner thinner and more compact. Larvae in July ; the flies 

 emerged the following April. In the last moult there is no increase in the 

 size of the head, but the larvs feed in the last stage. The $ larvfe are 

 smaller than the $ , and their heads do not enlarge at the moult before the 

 last, so they possess the anomalous character of having three stages with- 

 out any growth of the head. I have never observed anything of this kind 

 in the Lepidoptera, perhaps owing to their very different manner of moult- 

 ing. In the saw-flies the old head is split at each moult, as in the Lepi- 

 doptera at pupation only, and the new one has to grow aftCK the moulting 

 instead of largely before it, as in the Lepidoptera. 

 Hylotoma pectoralis, Leach. The red-headed birch saw-fly. 



A general description of this larva has been given by Rev. T. W. 

 Fyles (Can. Ent., XVIII., 38). I have a few details to add. 



Found on the black birch (Betula lenta) at Woods' Holl, Mass , and 

 Plattsburgh, N. Y. ; also common on the white birch (Betula papyrifera) 

 at Keene Valley, N. Y. 



Eggs. — Laid in a series of saw-cuts along the edge of the leaf between 

 the upper and lower epidermis, producing slight swellings 1.5 mm. in 

 diameter. The eggs are soft and white. 



The number of larval stages was not exactly determined, but what 

 evidence I have leads me to believe that there are eight, and I shall 

 describe them on that basis. 



First stage. — Head reddish ; width .6 mm. Body essentially as in 

 'the next stage (Keene Valley). 



Second stage. — Head shining black, a little paler at sutures, round, 

 about as high as wide, dented at clypeus ; width, about .7 mm. Thoracic 

 feet black, except at the joints. Body as in the next stage, but the pili- 

 ferous dots much smaller and so less distinct (Woods' Holl). 



Third stage. — Head light reddish-brown, shining, clypeus slightly 

 indented in black ; eye black in a black spot ; head well rounded, rather 

 higher than wide, full at vertex ; width, .9 mm. Thoracic feet large, 

 largely black ; abdominal feet small, their bases black and corresponding 

 spots on the apodal segments. Body shining yellowish-green, alimentary 

 canal obscured ; segments hardly annulate, but with three rows of large 



