-. 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 Lcpidoptera 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 Lcpidoptera 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 Lcpidoptera, belonging to the genus Heliconia, and that 

 there were several other kinds mingling with them which belonged 

 to difl"erent 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 Pieridi, which we have already noticed as usually having 

 white wings. The insect was clearly one of the Picridi, but 

 its clothing was that of Heliconia. 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 Lcpidoptera, 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 Picris with the garb of a Heliconia, 

 Nattire has provided it with a means of escape from insectivorous 

 creatures, that do not care for i/r/zV^;^/^^— natural selection being 

 at the bottom of the matter. 



The colours of both sexes are often the same in the Lcpidoptera, 

 but in some instances the ornamentation and tinting of the males 

 and females differ, as also do their growth and development. 



