128 EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 



pale yellowish and but little differentiated from the colorless wing, the pattern 

 strikingly resembles that of the adult insect. The white basal streak is distinctly 

 outlined, beginning at the base of the dorsum, where it seems to be homologous 

 j^^jjfj. IV. V yj: with the white streak separating Bands I and II, be- 



yond this lying over a trachea which extends through 

 ' / the cell just above the middle; its tip seems to coincide 

 with some portion of the white fascia separating Bands 

 Fig. 12. Early stage in the II and III. The white patch near the base of the dorsum 

 development of color in the wing • ^ identical with that in the adult and with the apex of the 



01 L. cratcegeUa. 



basal streak seems to constitute the last vestige of the 

 white fascia separating Bands II and III. On the dorsal margin, the outer edge 

 of Band III has shrunk away toward the base, and at the same time, there has 

 been a compensating extension of Band IV toward the base, resulting in a dis- 

 placement of the white streak, so that instead of being over vein 16, it is basal 

 to it, and vein Ih reaches the margin well within Band IV. The first pair of 

 streaks are already separated by a narrow line, which is not nearly as broad 

 internally as in the imago. At this stage, the costal white streak is not much 

 narrower on the margin than the dorsal. Bands V, VI and VII are situated 

 normally, except that V on the dorsum extends a little basally over the tip of 

 vein 2. These bands, while quite distinct on the margins and in the cilia, seem 

 to fade away in the middle of the wing. The entire middle of the wing, from the 

 tip of the first dorsal white streak almost to the extreme tip of the wing, remains 

 colorless, so that it is not possible to distinguish the bands from the interspaces 

 separating them. A comparison with the adult shows that this area coincides 

 with that to be occupied by the dark streak of scales through the middle and 

 by the apical patch of black scales. 



In a specimen somewhat more advanced, there has been a slight deepening 

 of color, but by no means, even in the golden color, has the adult shade been 

 attained. The color is still yellow, with no tinge of brown, unless the slight 

 darkening of the dorsal side of Band IV, especially toward the second white 

 streak, may be regarded as a foreshadowing of that color. The middle of the 

 wing from the tip of the first dorsal streak almost to the apex (except for the 

 grayish black scales to be noted below) still retains its whitish appearance. 

 Just before the apex and beginning just under the tip of vein 7, and extending 

 for a short distance along the underside of 7, are a number of grayish black 

 scales. These appeared first beneath the tip of 7 and were gradually extended 

 toward the base. The patch is broadest toward the apex, where it reaches al- 

 most across the wing. The inner edges of the first pair of streaks are more curved 

 than in the preceding specimen as a result of the broadening internally of the 

 yellow line separating them. The scales attached around the apex are yellow 

 and extend in an unbroken line to the second dorsal streak, that is, Bands V, 

 VI and VII have united along the termen. However, the scales whose apices 

 project beyond these and which are destined to constitute the iridescent blue 

 line in the cilia still remain pure white. 



