59° 
Color and Pattern and their Uses 
lines or striae. These striae vary in distance apart, on different scales, from 
.0007 mm., as in the scales of the great blue Morpho butterflies, to .004 mm., 
as in the sulphur-yellow butterfly, Catopsila eubule. 
The scales cover (in all but the few “clear-winged” moths) the wings 
on both upper and lower sides, 
being insecurely attached to the 
wing membrane by having their 
short pedicels inserted in little 
pockets or cups on the wing sur¬ 
face. They show an interesting 
and varying manner of arrangement. 
This arrangement varies from an 
extremely uniform one in the but¬ 
terflies and higher moths to one 
of much less regularity of disposi¬ 
tion in the lower moths. On the 
wings of a butterfly the scales are 
inserted with their pedicels directed 
„ . . . . . - toward the base of the wing in 
pig. 772.—A small, partly denuded part of 0 
the wing of a butterfly, Lycena sp., showing subparallel rows running trans- 
the scales and pits in a wing membrane, versely across the wing, i.e., from 
into which the tiny stems of the scales are ^ . 
inserted. (Photomicrograph by George O. anterior to posterior margin, and 
Mitchell; greatly magnified.) the scales in each row are at 
approximately equal distances apart. Their distance is less than the width 
of each scale, so that adjoining scales 
overlap laterally and thus make each row 
to be composed of two tiers of scales, an 
upper and an under one: the insertion- 
cups of one tier are very slightly but per¬ 
ceptibly advanced beyond those of the 
other tier. The scales of the upper tier 
alternate with those of the lower tier, and 
each upper scale overlaps laterally two 
under ones. But in addition to this 
lateral overlapping, the distance between 
the rows of insertion-cups is less than 
the leuo-th nf the ^rales that there Fig. 773.— Bits of denuded wing of a 
tne lengtn ot the scales, so that there butterflv. Gra-bta sd.. to show rows 
is an overlapping of the tip of the 
scales of one row over the bases of the 
scales in the next row in front. By this 
double overlapping there is formed a complete shingled covering of scales 
over each surface (upper and under) of each wing. 
butterfly, Grapta sp., to show rows 
of insertion-pits on upper and lower 
sides, with three scales in position. 
(Greatly magnified.) 
