458 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



a day or two the caterpillar died and turned whitish, the rows of black warts becoming 

 conspicuous. 



Full-grown larva.— Uesid coral-red, smooth above, deeply notched, but not tubercu- 

 lated, as is also the fourth (hrst abdominal) segment, which is humped, but the head 

 is smooth and shining, the hump dull red. The dorsal and anal regions dull yellow, 

 with black waved lines; four white subdorsal lines alternating with waved black 

 lines. Lower lateral yellow, with waved black lines. All the segments bear six or 

 eight setiferous black tubercles, looking like black sealing-wax. Anal segment jet- 

 black. Hairs all sordid white. Underside dull yellow, streaked with black waved 

 lines. Abdominal legs yellowish flesh color; thoracic feet black. Length 30™°> 

 (l.aS™"^). August 29-30. 



29. Centra borealis Boisd. 



The caterpillar here described occurred in August and September at 

 Bruuswick, Me., ou the aspen. It apparently differs from those of 

 C. occidentalis and cinerea in the longer spines on the prothoracic seg- 

 ment in the young larva, and Id the smooth slight rounded projections 

 which replace them in the full-grown caterpillar. 



Larva before last mo?<.— Length to base of caudal appendages 11""". Head large, 

 full, rounded, dark lilac-brown speckled with yellow, slightly wider than the body 

 except the front part of the prothoracic segment ; the latter very broad, over twice 

 as broad as long, the front edge laterally produced, and at each angle bearing a large 

 long spiny tubercle three-fourths as long as the segment itself ; the tubercle bearing 

 about twelve setiferous spines; across the posterior edge of the segment is a row of 

 four setiferous spines. On the back of the other segments are four short tubercles ar- 

 ranged in a short trapezium, and on each side of the segments are two smaller sharp 

 tubercles. The dorsal tubercles on the mesothoracic segment are larger than those 

 behind ; those on the metathoracic segment smaller than those on any other segment. 

 The body tapers gradually to the end ; the supra-anal plate longer than broad, 

 rounded, bearing two long large setiferous fleshy tubercles, which lie between the 

 bases of the spiny anal legs or filaments, which are about one-half or two thirds as 

 long as the body, and yellow, with two broad brown rings, and brown at the tip. 

 Body greenish yellow, marked as usual with lilac brown, this tint mimicking the 

 dead withered brown of the edge of poplar leaves of late summer; it is a dark lilac 

 brown with reddisTi brown and lilac brown patches, and in this way the caterpillar 

 mimics the dead stained portion of the leaf on which it feeds and thus escapes ob- 

 servation. From head to end of mesothoracic segment a brown patch, succeeded by 

 a pointed brown band which extends to the base of caudal appendages but contracted 

 ou the eighth abdominal segment, the dorsal tubercles of which are yellow. 



Larva after last molt. — Length, except caudal appendages, 17">'". Diifers from 

 foregoing stage in the prothoracic spiny horns being replaced by smooth, shining 

 tubercles with faint traces of the spines of the former stage ; the sides of the thoracic 

 segments more distinctly spotted ; with faint traces of broken yellow lines in the 

 middle of the body. 



The caudal appendages are soft and extensible on their outer third, 

 forming the "flagellum ;" and are quickly jerked up when the creature 

 is disturbed ; they are evidently delicate repellant organs. 



The close resemblance in the lilac-brown patches of this caterpillar 

 and others of the genus to the sere and brown edges of certain of the 

 leaves is remarkable, and plainly enough serves to protect the cater, 

 pillar from observation. I have observed the same in other Notodon- 

 tians, especially Schizura unicornis and allied forms. 



