158 NATURE SKETCHES IN TEMPERATE AMERICA 



white stripes decorates the sides, these being supplemented 

 with a small one at each extremity of the body. At the end 

 of the body there is a burnished black eye-like spot, which is 

 encircled with white. This spot marks, the situation of all 

 that remains of a slender recurved tail,, which is present in 

 the young larva but disappears after the first or second moult. 

 Sometimes these larvae are pale green, but they are usually 

 flesh-brown in color, as I have already described. At the 

 expiration of their period of feeding in August, they excavate 

 a hole in the ground and there transform into a reddish brown 

 pupa. It is not until the following June or July that the 

 exquisite moth emerges. It is about three to four inches in 

 the expanse of its wings. The initial illustration shows the 

 disposition of the markings on a ground color of reddish ash. 

 The thorax bears two triangular patches of rich chestnut- 

 brown. The front wings have two squarish markings, while 

 the hind wings have a pinkish hue shading into a red spot 

 near the middle, and the margin is ash colored behind. 



Of all the data furnished by the developmental history of 

 the sphinx moth larvae, Weismann '- says that three kinds of 

 markings occur. They are divided into longitudinal lines, 

 oblique stripes, and spots, the lines being the oldest. The 

 first rudiments of striping must have been useful since they 

 broke up the large surface of the body of the caterpillar into 

 several portions, and thus rendered it less conspicuous to its 

 enemies. Various facts tend to show that the oblique stripes 

 appear later than the longitudinal stripes in the ontogeny of 

 certain species. In following out this development in the 

 larvae it is found that characters vanish from a stage in the 

 same order as they were acquired in their evolution. The 

 oldest sphinx larvae were apparently without markings; they 

 were supposed to be protected only by adaptive coloring and a 

 large horn at the end of the body, and by being armed with 

 bristles. Their successors became longitudinally striped, acquir- 

 ing a sub-dorsal line extending from the horn to the head, as 

 well as a spiracular, and sometimes also a dorsal line. At a 

 later period oblique stripes were added, generally slanting across 

 the seven hindmost segments from the back towards the front 



' "Studies in the Theory of Descent." 



