EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 129 



A specimen at a somewhat later stage {Fig. 13) shows a httle more of the 

 orange brown tint, but the color is nowhere as deep as in the adult. The formerly 

 colorless area in the middle of the wing is still distinctly set apart from the rest 

 of the wing but has become narrower and is beginning to acquire a faintly yel- 

 lowish tinge. The white streaks are now definitely blocked out due to the 

 curving in of the yellow color; they are, however, still connected with the whitish 

 middle portion of the wing. The patch of blackish scales near the apex has 

 increased in extent and depth of color until its identity with the patch of hlack 

 scales in the apex of the adult wing is clearly established. It has now reached 

 its adult condition, and no further change takes place. ^j^jf^ jv y ^,j 



The early origin and differentiation of this patch of ^^T-^-' 

 scales shows clearly that it is a character quite sepa- ' ^ 



rate and distinct from the dark line of scales in the 



adult extending from it toward the base of the wing. Fig. 13. Later stage in the 

 The scales around the apex, yellow in the earher stages, development ^f color in the wing 



*^ ^ of L. cratoegella. 



are now tipped with pale brown, but the outermost row 



of scales are still whitish as before. There is some deepening of the ground 

 color just before the first and second pairs of streaks; the second dorsal streak, 

 however, is the only streak which can be said to have acquired a definite mar- 

 gin, and even this is pale brownish. The basal streak remains entirely un- 

 margined. 



In a specimen at a little later stage than that just described, internal margins, 

 though very pale, have appeared along all of the white streaks; that of the second 

 dorsal still continues to be in advance of the others. The margin of the first 

 costal streak has deepened somewhat, and there is a faint suggestion of gray 

 around its tip. A similar pale gray shade extends from the tip of the first dorsal 

 streak through the middle of the wing and around the tip of the second dorsal 

 streak. The ground color along the upper edge of the basal streak is somewhat 

 darkened, but there is no margin. 



In a wing at a considerably later period of development, the ground color 

 approaches the adult color over those areas where there are no brown scales. 

 The internal margins of the costal and dorsal streaks, as well as the upper margin 

 of the basal streak, are dark brown; the external margins of these streaks and 

 the margin around the tip of the basal streak while present are not as dark as 

 in the adult and show a decidedly grayish tinge. This same gray color is pro- 

 longed from the tip of the first dorsal streak along the middle of the wing in the 

 area formerly colorless but is much paler than in the adult. This difference from 

 the adult color is especially noticeable above the patch of black scales, where 

 in the imago there is a decided deepening of color, almost blending with the 

 black patch. There is but very httle deepening of color between the first and 

 second dorsal streaks, and the margin of the second dorsal streak is neither as 

 deep nor as wide as in the adult. The darkening of scales in the cilia started in 

 earher stages stih continues. There is, however, no change from the colorless 

 condition of the scales which are to be deep iridescent blue. 



