CHAPTER VII 
THE COLOURS OF THE LEPIDOPTERA 
Insect Coloration and its General Relation to Physiology— 
Pigments of Caterpillars—Intrinsic and Derived Pigments 
—Mr. Poulton’s Experiment—Meaning of Derived Pig¬ 
ments—Other Characters of the Coloration of Caterpillars 
—Colours of Butterflies, Pigmental and Optical Colours 
—The Pigments of the Pieridae—Pigments of other 
Butterflies—Origin of the Pigments of Butterflies—Con¬ 
trast between the Pigments of Butterflies and those of 
Caterpillars—Pigments and Mimicry. 
The colours of insects are in many cases so con¬ 
spicuous that they have always attracted much 
attention, and of late years few biological subjects 
have been more keenly debated than the meaning 
and uses of the tints and markings of caterpillars 
and butterflies, bees and flies. The frequent simi¬ 
larity in colour between insects and their environment, 
or between insects not nearly related, or on the 
other hand the exceeding conspicuousness of some 
well-protected insects, are facts which are obvious to 
every one, and which have therefore attracted wide¬ 
spread interest. Until very recently, however, this 
interest has been chiefly confined to the external 
