136 THE CANADIAN ENTOMOLOGIST. 



anterior. Tubercle iv, behind the spiracle, \- aliiiosi immediately 

 below the spiracle, both enclosed in the stigmatal band, the former 

 near the upper edge and the latter near the lower edge. Thoracic 

 feet pale, somewhat translucent; prolegs concolorous with sub- 

 ventral area; crotchets slightly pinkish; legs on segment 10 normal, 

 on segments 9, S and 7 much reduced, the latter being the smaller 

 and decidedly rudimentar\-. Length of full grown lar\a at rest 

 26 mm. 



The Pupa. — -Length 12-1-i mm.; witlili at widest \)\xn. ") mm. 

 When newly formed green, soon changing to pale brown, and later 

 to dark reddish-brown; thorax and wing-covers darker, almost 

 blackish, wrinkled; abdominal segments coarsely pitted on anterior 

 three-quarters and minutely pitted on posterior one-quarter. 

 Spiracles pale yellowish in centre. Cremaster two-spined, the 

 spines stout and arising from either side, curved outwardly from 

 towards the tip, and forming, almost, a perfect letter U. 



Food Plant. — All lar\a' reared at Ottawa were fed on the 

 foliage of Aspen Poplar, Populus tremuloides Mich.x. This tree is 

 the only food plant upon which we have found the larvae feeding 

 under natural conditions. 



Habits of Larva. 



During the different instars the larva.' spun considerable silk. 

 I'nder natural conditions, at Aweme, Man., they have been fre- 

 cjuently observ^ed hanging at the end of a silken thread spun from 

 the branches of Aspen Poplar. This habit and that of looping 

 when walking corresponds well with many of the Geometridae. 

 A ms. note by Fletcher reads as follows: "A semilooper, the three 

 first pairs of abdominal legs not used in walking, although apparent. 

 When at rest the young caterpillar rests as a geometer on the anal 

 and fourth pairs of abdominal prolegs, with the front of the body 

 raised. The larva? have the same habit as Brephos. infans of 

 catching several leaves tightly together with single threads, and 

 when resting, either lie along the petiole or inside a curl of a young 

 leaf. When they began to feed, they attacked the edge of a leaf 

 or ate straight into the surface either above or below." 



When mature the larvie entered the earth to pupate. The 

 larvae studied in 1915 were full grown on May 15 and 16. By 

 May 20 all had changed to pupa\ The earthen cell is slight. 



