124 EVOLUTION OF COLOR PATTERN IN LITHOCOLLETIS. 
been preserved in its original primitive eondition as seven distinet transverse 
bands; fusions either partial or entire have taken place between two or more 
adjacent bands. Displacements have also occurred, due to a shrinking away 
of eolor from one side of a white interspace and its extension over the white on 
the other side. Finally, some of the bands may have shrunk away almost 
entirely. 
The following is a list of the species in which the development of the pattern 
has been traced from the first appearanee of color to the adult markings: 
Species in which two or more of the bands 
Lithocolletis tiliacella Cham. have been preserved almost in their 
Lithocolletis tritenianella Cham. primitive condition as respects position 
and shape. 
Lithocolletis crategella Clem. | Species in which changes in shape or 
Lithocolletis ostryefoliella Clem. position or both and more or less com- 
Lithocolletis lucidicostella Clem. plete fusions of some of the bands have 
Lithocolletis morrisella Fitch taken place and certain differentiations 
Lithocolletis hamadryadella Clem. . апа specializations have appeared, such 
Lithocolletis bethunella Cham. as the development of black scales at 
Lithocolletis ulmella Cham. places other than those directly con- 
Lithocolletis esculisella Cham. tiguous to the white interspaces be- 
Cremastobombycia ignota F. and B. | tween the bands. 
In the following species, the development of the pattern was observed only 
in part for the purpose of comparing the development of certain characters in 
these species with that of similar characters in related species, or with a view of 
determining the relative time of appearance of certain characters: 
Lithocolletis hageni F. and B. 
Lithocolletis robiniella Clem. 
Lithocolletis caryefoliella Clem. 
Cremastobombycia solidaginis F. and B. 
In all of the species studied, the wings are at first transparent and glassy 
in appearance, corresponding to the period, as observed by Mayer (796), before 
the protoplasm has been retracted from the scales. Following this is the so- 
called white stage, in which the wings appear by reflected light almost pure white 
and by transmitted light pale buffish, due to the hemolymph contained within 
them. The scales are at this period colorless and transparent, containing only 
air. The white stage lasts from one to two days, giving way to a pale yellow 
over certain defined areas, as the hemolymph enters the scales and the pigment 
begins to form. This yellow color may be preserved throughout pupal develop- 
ment almost as originally laid down, or it may go through a process of transfor- 
mation before reaching the adult condition. In either event, it gradually deepens 
in tint and constitutes the ground color upon which the dark streaks (margins) 
a D E N ye beh AG E qat EE EE 
