COLORS OF INSECTS. I 25 



composed of several colors, and in all he found a surprisingly large percentage 

 of black. The colors of other orders of insects have not been studied as 

 regards their purity. 



EVOLUTION OF THE COLOR PATTERNS OF INSECTS. 



Studies in the evolution of the color patterns of insects have been made 

 almost entirely upon Lepidoptera ; in fact, outside of this order only two 

 papers, excepting short notes scattered here and there, have been published. 



LAWS OF COLORATION. 



The first author to deal with the laws of coloration in insects was Higgins, 

 who maintained that the simplest and most fundamental color pattern is a 

 uniform tint, and that later the pigment developing along the nervules forms 

 darker markings which follow the lines of the nervules. Spots and ocelli he 

 believed to arise by the migration of crescent-shaped areas from the nervules 

 into the interspaces. The ontogenetic studies of von Bemmelen, Hasse, 

 Mayer, and von Linden produce no data in support of this view. On the 

 contrary, Mayer and von Linden show that the scales over the nervules and 

 along their courses remain uncolored until after other parts are pigmented. 

 It was shown by Darwin that ocelli can be traced through a continuous series 

 backward into dark spots with lighter centers. Scudder and Bateson, in 

 Lepidoptera, showed that ocelli are always located in interspaces and rarely 

 upon the nervules. Mayer advanced the following laws as those which gov- 

 ern coloration in Lepidoptera : 



(a) Any spot found upon the wing of a butterfly or moth tends to be bilaterally 

 symmetrical, both as regards form and color ; and the axis of symmetry is a line passing 

 through the center of the interspace in which the spot is found, parallel to the longi- 

 tudinal nervules. (b) Spots tend to appear, not in one interspace only, but in homolo- 

 gous places in a row of adjacent interspaces, (c) Bands of color are often made by 

 the fusion of a row of adjacent spots, and, conversely, chains of spots are often formed 

 by the breaking up of bands, (d) When in process of disappearance, bands of color 

 usually shrink away at one end. (c) The ends of a series of spots are more variable 

 than the middle. This is only a special case of Bateson's law. (/) The position of 

 spots situated near the outer edges of the wing is largely controlled by the wing folds 

 or creases. 



The same author (Mayer) later distinguishes three kinds of markings on 

 the wings of Lepidoptera spots, bands, and combination markings the latter 

 being a combination of spots and bands and more numerous than the first 

 two classes. He also gives the following laws concerning their behavior : 



Bands, rows of spots, and combination markings are usually unbroken, of uniform 

 color, and isolated one from another; and only rarely do we find them broken, parti- 

 colored, or fused one with another. All departures are much more apt to affect the 

 ends than the middle of a marking. Rows of spots and combination markings are 



