lU 



134 EVOLUTION OF COLOR PATTERN IN LITIIOCOLLETIS. 



V, VI and VII are still separated from one another by curved white fascise 

 extending entirely across the wing and into the ciha {Fig. 18). The second 

 pair of white streaks are still connected^ but Band IV is beginning to project 

 i,jr,7n jjr ^- into them in the middle of the wing. At this time the 



'^" ground color of the wing is a pale straw and lacks alto- 

 * ^ gether the golden brown of the adult. The internal 

 margins of the first and second dorsal streaks are begin- 

 FiG. 18. Wing of L. hagcni at ning to form. The inner edges of the bands^ border- 

 the first appearance of the dark -^^ ^^^ ^^^^^^^ outwardly, present much the Same 



appearance as they do in species where the white 

 streaks never acquire external margins; that is, the ground color fades gradu- 

 ally into the white. 



A dark line in the cilia begins to form soon after this; the scales showing 

 the brown pigment at this time are not those which will be bluish iridescent in 

 the imago; these latter remain pure white and only acquire their pigment later. 



In the third specimen studied, the extent of the white streaks has been finally 

 limited, and the golden brown color of the adult has been attained. AU of the 

 internal margins of the streaks, the dark scales at the apex of the first dorsal 

 streak, those connecting the tips of the second pair of streaks and the two leaden- 

 colored lines of scales running across the wing from the tips of the third and 

 fourth costal streaks are present. In addition, external margins are present 

 on the white basal patch and on the first dorsal streak. All of these borders 

 are as they will appear in the adult. In this specimen, there was no indication 

 of a deepening along the upper side of the basal patch. However, this obser- 

 vation cannot be accepted as altogether reliable in indicating the time of appear- 

 ance of the margin of the basal streak, since the specimen was evidently ab- 

 normal, the apical dot not being present. No other specimens were available 

 to decide the point. Imagoes of this species are occasionally found which lack 

 both the apical dot and the dark margin along the upper side of the basal patch. 



LithocoUetis aesculisella Cham. 



The species heretofore studied have been those belonging to the group 

 having cylindrical larvae and characterized by the principal margins of the 

 white streaks being internal. This species (Fig. 70, PI. IV) and those following 

 have the so-called flat type of larva, and the white streaks of the imagoes have 

 their darkest margins on the outer side. That is, in the former group, the 

 tendency is for the color bands to acquire first, dark margins on their outer 

 edges; in the latter group, the condition is reversed, and the dark color appears 

 first on the inner edges of the bands. 



In L. cBsculisella, at a period when there is scarcely any differentiation 

 between ground color and bands, the pattern appears to be laid down almost as 

 in the adult (Fig. 19). The bands are very pale buff, and judging from their 

 uniform color, appeared simultaneously. The pale shade at the base which 



