74 TRANSFORMATIONS OF INSECTS. 
upon the colourless rays of light that fall upon them, and 
decompose them into a variety of tints that emulate the rainbow. 
Many animals, such as birds and insects, live beneath the 
branches and amongst the sombre foliage of trees, and _ their 
colours are correspondingly quiet in tone; they take on a livery 
which enables them to escape observation, and they thus owe 
their safety to their mistress Nature. Hundreds of caterpillars 
escape destruction and extirpation in this manner; but the but- 
terflies of the Lepidoptera do not hide, and they rather glory in 
the brightness of the full light of day. 
The inquiry is rather complicated by the fact, elaborated by 
Wallace, that Lepidoptera which belong to different genera have 
often a similarity of colouring; but a hint from Mr. Bates, that 
admirable naturalist, who has given us such vivid descriptions of 
tropical nature in the district watered by the Amazons, throws 
no little light upon this difficult subject. He noticed immense 
flocks of Lepidopterc, belonging to the genus Heliconia, and that 
there were several other kinds mingling with them which belonged 
to different genera. Now these strangers in the crowd borrowed 
the Heliconian decorations, and would have passed muster to 
superficial observers as having a legitimate right to them. But 
the eye of the entomologist discovered that some belonged to 
the Pzeridi, which we have already noticed as usually having 
white, wings. The insect was clearly one of the Pzerzdz, but 
its clothing was that of /e/zconza. It was a dove in peacock’s 
attire, all glowing with red, yellow, and dark colours. Some 
of the other butterflies of the crowd had the same habits and 
peculiarities of flight of the Lepidoptera, whose garments they 
imitated. These were not accidental mimicries, for the descendants 
of these masqueraders do the same thing year after year. Why 
does Nature then mimic the decorations and colours? Mr. Bates 
suggests that in clothing a Pzeris with the garb of a Hediconza, 
Nature has provided it with a means of escape from insectivorous 
. creatures, that do not care for He/iconte—natural selection being 
at the bottom of the matter. 
The colours of both sexes are often the same in the Lepidoptera, 
but in some instances the ornamentation and tinting of the males 
and females differ, as also do their growth and development. 
