72 MEMOIKS OF THE NATIONAL ACADEMY OF SCIENCES. 



ciiterpilliir is at rest thev are held close together in a recurved position and in the grown-up larva 

 when touched they are not moved or the body jerked in response to such stimulus. They are 

 adorned with white, hlunt spines, which are often tipped with black. 



"'The 'sitver horns' on the third to the sixth abdominal seo;mpnt>; are now one-sixteenth to 

 one-eighth of an inch long, bright pink inside and burnished silver externally. The number of 

 these "silver horns" varies in different larvfe, some having them only on the fourth and sixth 

 abdominal .segments; others have them on the fifth, seventh, and ninth segments; still others have 

 them on the second, fourth, sixth, and seventh segments." (Papilio, II, -1:9.) '"I have now to 

 add that this year I reared three larvie having these silver horns on evei'y segment except the 

 twelfth; still the imagines from these three larvas did not differ from the ordinary' form." 

 (Jewett, Papilio. II, 14-i.) 



The horn on the eighth alidominal segment is now only about one-fourth shorter and thicker 

 than the thoracic spines, and is of the same color and structure, the spinules being conical, 

 rounded, blunt, white, and bearing a fine bristle. 



On abdominal segments 1-7 are two dorsal rows of acutely conical spines, which are recurved 

 and directed backward. Those on the fourth and sixth abdominal segments are twice or thrice 

 as large as those on the other segments (1-3 and 4 and T), and provided with three or four blunt 

 spinules; the spines themselves are roseate on the inner side, and externally brilliantly painted 

 with a pearly silvery white, giving off" all the colors of the rainbow during the movements of the 

 animal. The corresponding spines on the other segments are painted in the same fashion, though 

 less brilliantly. 



I find, as did Jewett, that the number of the dorsal '"silver horns" varies, one larva having 

 but two pairs, one on the fourth the other on the sixth alidominal segment, while in another 

 there is a pair on the second atxlominal segment (fig. 8). The degree of specialization of these 

 dorsal spines varies, but those of the first abdominal segment are always smaller than any behind, 

 both in stages IV and V. This stage in armature differs from IV in the much shorter and 

 .stouter thoracic horns, and in the differentiation of the two or three pairs of dorsal al)dominal 

 silvery spines. 



On the side of the body from the third thoracic horns to the eighth abdominal sjjiracle is a 

 bicolored stripe; it is pure mai-ble-white below, and above rosy purple, and is interrupted by the 

 wax-colored spiracles, which extend above the upper limits of the reddish line. The suraual 

 plate is very large and long, deepiv divided at the end, the two forks being, like the surface, 

 coarsely gramdated with stout short conical spines; the plate is green, with the edge straw- 

 yellow. There is a luinute median spine on the ninth abdominal segment. Each abdominal 

 segment with two dor.sal transverse rows of white, bead-like, coarse granulations. Below the 

 l)icolored lateral stripe is a black, double, conical spine on each segment, and underneath on 

 abdonunal segments 1, 2, 7, and 8 is a group of unecjual. smaller. l)lack, sharp spines. The body 

 beneath is granulated with white, and also on the sides, as well as above. 



The thoracic legs are black, partly greenish beneath; the abdominal legs, including the anal 

 pair, are greenish, with a group of singular black piliferous spines, while some of the spines are 

 tipped with white. 



The general color of tlie body is of nearly the same luic as the under side of the leaves of 

 the honey-locust, and thus colored it is partly assimilated and piotei'tcd l)y its color, while the 

 horns arc in general like the spines of its food plants. On the other hand, the gleaming silvery 

 spines certainly render the creature conspicuous, as well as the lateral parti-colored l)and. 



It would ai)pear proba))le that the formidable spines of the grown-up caterpillar save it not 

 infrequently from being swallowed by birds; though the horns are probably of greater use in 

 the earlier stages, when they are nuich longer and much more movable, in frightening away 

 ichneumons and Tachina'. For exam])le. even when "2(1 mm. in lengtii. a larva was seen when teased 

 to spread apart its great arm-like horns, while the full-fed ones did not notice such stinniius. 



