28 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



1. The green form. — (PI. XXI. tig.l, see also Riley's ligure in Anier. Ent.. i., PI. 1) {a) It lives, 

 or at least the examples collected, lived on the hickory. The general hue is a rather dark olive- 

 green, becoming slightly paler above, and pale turquoise blue around the bases of all the spines. 

 The seven oblique lateral inf raspiracular bands are paler, of a deep pea green. ' ih) The green- 

 orange form. It lives on the hickorv. It differs from the entirely green form in the orange tint 

 on the back of al)dominal segments 1 to 8. The lateral oblique bands are turquoise blue, and the 

 blue around the base of the spine is deeper in hue, while the ring around the spiracles, instead of 

 being orange-red as in «, is now deep blue. 



2. Tlie blue and orange form. — PL XXII, fig. 1. It feeds on the butternut. The entire body 

 above is turquoise blue, including the oblique lateral stripes, which are deeply shaded on the lower 

 edge. The spiracles are tinged with orange, and there is a patch of orange behind each abdominal 

 spiracle of the third and fourth abdominal segments. On asking Mr. Verrill whether the colors 

 of his photographs are not too bright he replies: '"The color, however, is none too bright even 

 on the blue form; in fact, the brilliancy of this variety' can hardly be imagined. It is such an 

 intense opalescent l)lue that it resembles blue enamel more than animal tissue. When the cater- 

 pillars are first secured I always make a hurried water-color sketch to be sure of the exact shade, 

 and if in the photograph the tints are not true thej^ are touched up by hand." 



The irown form, stage IV. — (PI. XXIII, rig. 1.) A brown form (a) was found feeding on the 

 ash. The ground color appears to be an olive green, with a faint orange tinge shading into a 

 reddish brown. The horns and spines are all dark black brown. The oblique lateral bands are 

 very conspicuous, and are of a bright olive-green hue. (5) The pink form (PI. XXII, rig. 2). also 

 living on the ash, was in the fourth stage. The body is uniforndy pale reddish or madder brown, 

 with a slight pink or carmine tinge. The two large dark thoracic dorsal patches instead of being 

 black are deep madder brown; the head, all the legs, both thoracic and abdominal, and the 

 armature, as well as the suranal plate, are of the same hue as the body. Tlie ohlique lateral 

 bands are much paler, almost pinkish." •■ 



It would be most desirable that some future observer favorably situated should ascertain the 

 exact conditions of the environment under which these colored forms have been produced, how 

 permanent they are, and whether hereditary or only confined to the lifetime of the individuals 

 themselves. 



In 1892 Professor Poulton'' studied experimentally the adjustment of the colors of the larvEe 

 of AmphidaKis Vetularia to those of their environment, and in 1903'' he published the results of 

 experiments on another geometrid larva. Odontopera hidentata. This larva is extremely sensi- 

 tive, with a power of adjustment about equal to that of the Amphidasis, "'the most sensitive 

 larva hitherto known." A large number of records proves that the larvse, in the great majority 

 of cases, rested by day upon the ol)jects, lichen-covered twigs, whose hue they afterwai'ds came 

 to resemble, though this is "•i^robably not the case in the earliest stages, when the larva? doubt- 

 less rest on the leaves and stalks." '"The effect of green leaves alone upon hidentata is the same 

 as that obsei'ved in many other larvie, Noctua? as well as Geometrje, viz, the reduction of the 

 brown ground color to a very pale tint which would be far less conspicuous than the more ordi- 

 nary appearance." 0. hidentata appeared to be more sensitive to lichen than A. Jhtidaria, but 

 less sensitive to green leaves, though the two species are "'about equal in the power of color 

 adjustment." And Poulton adds, "■ lichen uuist have been the cause of the h,tidaria larva-, with 

 one exception, becoming green, for ordinary bark tends strongly to the production of dark forms 



« From Mr. Verrill I have also received colored photographs of a green and of a pinkish form of Ampelophaga 

 myron on the grape vine; also of the red form of Cressonia jtigknidis, and a red form of Apalda brumosa. 



''Further experhnents upon the color relation between certain lepiilojiterou.? larvpe, pupa?, cocoons, and imagines 

 and their surroundings. Trans. Ent. .Soc. London, Dec, 1892. 



''Experiments in 1893, 1894, and 1896 upon the color relation between lepidopterous larva' and their surround- 

 ings, and especially the effect of lichen-covered bark upon Odottlopera hidentata, Gastropacha guercifolia, etc. Ibid., 

 Oct., 1903. 



