THE CANADIAN ENTOMOLOGIST. 247 



and substigmatally, forming a series of very black subdorsal patches or 

 spreading largely over the body. At the end of this stage the larva enters 

 the earth without moulting. 



Cocoon. — Formed beneath the ground ; elliptical, rather thick, firm, 

 opaque, black. Size, n x 4.5 mm. . Imagos appeared August 1. Larvae 

 found on the leaves of Betula populifolia at Woods' Holl., Mass., and 

 Plattsburgh, N. Y. 

 Fenusa varipes, St. F. 

 (The imported alder leaf-miner.) 



Abundant on Alnus serrulata at Woods' Holl., Mass., causing the 

 leaves to turn brown and fall. 



Egg. — A slight circular swelling in the leaf, visible on both surfaces, 

 0.5 in diameter. The egg is thin, delicate, milky white, about 0.3 mm 

 in diameter, inserted under the epidermis by a saw cut. 



First stage. — Mines under the upper epidermis usually less than 1 mm. 

 in diameter, rarely as large as 1.5 mm., starting from the egg puncture. 

 Head much flattened, broader than long, mouth parts projecting, the 

 lateral lobes bulging, pale watery brownish ; width, 0.25 mm. Body 

 flattened, deeply incised, joint 2 wide, joints 3-4 rapidly tapering, the 

 rest of even width, joint 13 rounded. Feet imperceptible with a lens. 

 Colour translucent watery, scarcely whitish, alimentary canal green. 

 Length, 1 mm. 



Second stage. — Like the preceding stage, but thoracic segments larger 

 and body more deeply incised. Milky translucent, the alimentary canal 

 green, head brownish, 0.3 mm. wide. Feet very rudimentary, but visible. 

 Cervical shield present, large, not very distinct. Burrow about 3 mm. 

 diameter. 



Third stage. — As before. Width of head, 0.4 mm.; diameter of bur- 

 row, about 6 mm. 



Fourth stage. — Much as in the next stage. Cervical shield covering 

 the anterior half of joint 2, very faintly brownish, as are the thoracic feet. 

 Head rather paler than in the next stage, 0.55 mm. wide. Burrow about 

 10-12 mm. in diameter. 



Fifth stage. — Head much flattened, mouth projecting in front, clypeus 

 occupying the central third of what is the upper surface ; lobes rounded, 

 projecting laterally ; ocellus nearly central. Colour honey-brown, paler, 

 almost whitish toward vertex, which is withdrawn beneath joint 2 ; mouth 

 dark brown, eye black; width, 0.75 mm. Abdominal feet very rudi- 



