1 88 ENTOMOLOGY 



condition to a distinct line or band of dark color parallel to the margin. 

 Or the marginal shade may, in a similar way, break up into two or more 

 transverse and parallel submarginal lines, a very common style of 

 ornamentation, especially in moths. Or, again, starting with the 

 submarginal shade, this may send shoots or tongues of dark color a 

 short distance toward the base, giving a serrate inner border to the 

 marginal shade; when now this breaks up into one, two, or more lines 

 or narrow stripes, these stripes become zigzag, or the inner ones may be 

 zigzag, while the outer ones are plain a very common phenomenon. 



" A basis such as this is sufficient to account for all the modifications 

 of simple transverse markings which adorn the wings of Lepidoptera." 



Briefly, one or more bands may break up into spots or bars, the 

 breaks occurring either between the veins or, more commonly, at the 

 veins; and in the latter event, short bars or more or less quadrate or 

 rounded spots arise in the interspaces. From simple round spots there 

 may develop, as Darwin and others have shown, many-colored eye-like 

 spots, or ocelli. 



Mayer gives the following laws of color pattern: "(a) Any spot 

 found upon the wing of a butterfly or moth tends to be bilaterally sym- 

 metrical, 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 longitudinal nervures. (b) Spots tend to appear 

 not in one interspace only, but in homologous 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. (e) The ends of a series of spots 

 are more variable than the middle. (/) The position of spots situated 

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

 or creases." 



These results have been arrived at chiefly by the study of the varia- 

 tions presented by color patterns. 



Variation in Coloration. It is safe to say that no two insects are 

 colored exactly alike Some species, however, are far more variable 

 than others. Catocala ilia, for example, occurs under more than fifty 

 varieties, each of which might be given a distinctive name, were it not 

 for the fact that these varieties run into one another. One may examine 

 hundreds of potato beetles (L. decemlineatd) without finding any two 

 that have precisely the same pattern on the pronotum. The range of 



