CHAPTER VIII 
THE COLOURS OF INSECTS IN GENERAL AND OF 
SPIDERS 
Optical and Pigmental Colours in Insects—Colours of the 
different Orders of Insects—Colours and Pigments of 
Orthoptera Optical Colours of Neuroptera—Coloration 
of Beetles — Pigments of Hemiptera—Colour Resem¬ 
blances between Diptera and Hymenoptera—Contrast 
between Coloration of Lepidoptera and other Insects— 
General Aspects of Insect Coloration — Variation in 
Colour: (i) Natural, (2) Artificially produced — The 
Colours of Spiders : (1) Optical, (2) Pigmental—Develop¬ 
ment of Colour—Variation in Colour—Colours of the 
Sexes—Markings of Spiders. 
Among insects other than butterflies the colours 
are often striking and beautiful, and are again 
divisible into pigmental and optical. Probably, 
as a rule, when an individual exhibits brilliant 
colouring, this is mainly due either to pigment 
or to structure, the two types of colouring being 
rarely both conspicuous at the same time. But 
this is true only of the bright pigments, the dark 
being common in insects displaying much structural 
colour. This is due to the fact that the dark pig¬ 
ments are present in excess only when the cuticle 
