EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 125 



and spots are to appear. The development of the pattern takes place very 

 rapidly during the last part of the pupal state. The time intervening between 

 the first appearance of a tinge of yellow on the wings and the emergence of the 

 imago is largely dependent upon temperature and is often less than twenty-four 

 hours. Development takes place more rapidly in day time than at night and 

 is strikingly retarded during cloudy weather. 



Lithocolletis tiliacella Cham. 



In the first specimen examined, the wings were removed from the pupa at 

 a very early stage of development. The yellow color is scarcely differentiated 

 from the clear buffish white wing {Fig. 9) . The only bands ^ jtr jy 



which can be distinguished are II, III and IV. Band II 



crosses the wing just before the tip of vein 12, thus occu- ' j 



pying its primitive and typical position. It is the palest 



and least defined of any of the three bands present. Its Fig. 9. Early stage in the 

 outer edge is definitely defined, but its inner edge fades d^^^^^P^^^t ^f f^^ ^^ t^e 



^ ^ ^ ^ ^ wmg 01 L. hhaceUa. 



mto the clear basal part of the wing, the color being ex- 

 tended farthest toward the base just within the costal and dorsal margins. 

 Band III has also preserved its primitive position and form. It is somewhat 

 darker than II, but uniformly colored throughout its breadth, the outer edge 

 not darkened. Its width is scarcely greater than that of the clear band pre- 

 m jv V ceding it. Band IV is the most deeply colored as well 



JI \ I ; VI YU 



^ ' . -' i as the broadest of the three bands; it is of the same 



i ' breadth as in the adult. Even at this early stage it is 



prolonged outwardly almost to the end of the cell. The 



Fig. 10. Later stage in entire apical part of the wing and cilia are of the 



the So^nklr'" " ^^^^^ ^hi^i^h ^^1^^^ ^he^^ '^^i^g ^o indication whatever of 



bands. 

 The wing in the next stage examined shows considerable advance over the 

 stage just described {Fig. 10). There has been a decided deepening of color, 

 and the adult pattern has been laid down, with the possible exception of Bands 

 VI and VII, which have not as yet been clearly differentiated as bands although 

 there is a faint yellow tinge in a few of the scales in the apical portion of the wing. 

 These bands are usually indistinct and sometimes absent even in the adult. 

 Band I is united with Band II along the costa; this condition was apparently 

 not produced by the independent origin of Band I and its later fusion with II 

 but by a uniform and gradual deepening of the wing below the costa. The 

 outer edge of Band II is now somewhat bent outward in the middle, and the 

 scales in the middle of the outer edge are beginning to deepen in color, thus 

 foreshadowing the appearance of the dark margin, but there is as yet no hrown 

 pigment in the scales. Band III is also somewhat bent outwardly as in the 

 adult, and its dark margin is present on the costa and dorsum only, the costal 

 margining being much less distinct than the dorsal; neither extends more than a 



