Color and Pattern and their Uses 



589 



That our discussion of insect colors may be made more explicit we may, 

 with the foregoing account of the causes and kinds of colors in mind, 

 endeavor to see just how the color-pattern of a certain single group of insects 

 is produced. This group is that of the moths and butterflies, in which 

 color and pattern obviously reach a maximum of development and special- 

 ization. 



If the wing of a moth or butterfly be rubbed gently between finger and 

 thumb, a spot on the wing will soon lose its color and become transparent, 

 while on finger and thumb will be found a fine sparkling powder, the "flour" 

 of the miller-moth, the jewel-dust of the butterfly. This dust, rubbed on 

 a glass slide and examined under the microscope, will be seen to be com- 



FiG. 770. — Single scale from moths and butterflies, a, from Tolype velleia; b, from Cast- 

 nia sp.; c, from Micropteryx aruncella. (Greatly magnified.) 



posed of symmetrical tiny scales, each composed of a flattened blade and 

 short stem or pedicel (Fig. 770). A considerable variety of shape will be 

 noticeable among these scales, and if scales are rubbed from other moths 

 and butterflies, many new shapes will be found. But through all this diver- 

 sity of appearance, a fundamental plan of make-up 

 may be recognized in each of these minute structures. 

 Most commonly the scales are more or less ovate in 

 outline with the little stem projecting from the narrower 

 end. The broader end has its margin entire or with 

 dentations of varying depth and number. These den- 

 tations may be so deep that the scale looks like a 

 several-fingered little hand. In size the scales vary 

 from .07 mm. (jl^ inch) to .8 mm. (^j inch) if we Fig. 771.— Scale of 

 exclude the long hair-like forms common near the base Hepialus mcglash- 



" am, showing pn- 



of each wing, and also the slender elongate ones mary and sccondarj- 

 which project from the wing-margins. In width the striation (Greatly 

 scales vary from hair-like to a breadth of .4 mm. {-^^ inch). 

 Some scales are as broad as long, or even broader than long. Running 

 longitudinally from base to outer margin are many fine little subparallel 



