[FLETCHER & GIBSON] SOME SPECIES OF CANADIAN LEPIDOPTERA 68 
body. The dorsal band is of two pale white stripes which show the deep 
green dorsal vessel between. Sub-dorsal stripe pale, narrow and some- 
times interrupted, but clearly discernible for the whole length of the 
body, as far as the anterior portion, of segment 13, where it terminates 
on each side of the larva at one end of a bracket shaped fold which ex- 
tends across the dorsum. Substigmatal stripe, which is by far the 
most conspicuous marking on the body, creamy white, washed with 
gamboge yellow and very finely edged above for its whole length (five 
specimens) with reddish-purple. This purplish tinge can also be noticed 
when the caterpillar moves its body, as a purplish reflection on the skin 
extending a short distance above the stigmata and up the intersegmental 
fold but very apparent all over the ventral surface. The substigmatal 
stripe starts at the base of the antenna, runs along the lower side of the 
face and expanding to its greatest width on the 3 thoracic segments 
narrows down again rapidly to half the width on segment 5, and then 
narrows slightly across segments 7, 8 and 9, where it is narrowest. It 
widens again gradually from 9 to 13 where it is as wide as on segments 
2 to 4. It terminates beneath the tip of the anal flap, but does not 
quite meet below the anus. Spiracles bright orange, narrowly ringed 
with black. Body smooth, but bearing yellowish-white, low, piliferous 
tubercles, bristles short and very slender. Above each spiracle, on 
two between dorsal band and 

abdominal segments are seven tubercles 
subdorsal stripe, and below this five, arranged in an oblong square with 
one in the centre, and anterior to each spiracle is a minute white dot. 
Thoracic feet and prolegs concolorous with venter; claspers of prolegs 
pale with ‘brownish hooks. 
Length of mature larva when extended 43 mm., width at widest 
segment 6 mm. 
On the 28th May two of the larve entered the ground, and two 
days later a third specimen buried. On, the 10th June, a fourth speci- 
men which had not developed as quickly as the others was full grown, 
and by the 11th had spun a cocoon between two leaves. The specimens 
which buried formed a distinct earthen cell, considerably strengthened 
with silk. The cocoon made among the leaves by the fourth specimen 
was slight, but tough, and of a whitish colour. 
Pupa.—tLength 18 mm., width at widest part 6.5 mm., dark brown, 
almost black, with a faint reddish tinge in places; thorax and wing-cases 
conspicuously wrinkled; abdomen slightly wrinkled and coarsely punc- 
tured ; no cremaster. 
Food plant.—Aspen poplar, Populus tremuloides, Michx. ,Other 
poplars, as well as willow, elm and birch were offered to the larve, but 
they would not eat them. 
