KDomledge & Selentifie flems 



A MONTI II A' JOURNAL OF SCIENCE. 



Vol. I. No. 



[new skrifs ] 



APRIL, 1904. 



E Entered at 1 

 Stationers' Hall.J 



SIXPENCE. 



> Contents and Notices. — See Page VII. 



The Protective 

 Resemblance of Insects. 



By Percy Collins. 



The story of insect life has many phases of entrancing,' 

 interest ; nor is this altogether surprising when we 

 remember that the earth, the air, and the water are alike 

 peopled by the vast army of the six-footed. These varied 

 conditions of life have left their mark not only upon the 

 habits and movements of insects, but upon their colour, 

 their form, and their instinctive attitudes of repose. So 

 that although insects are more diverse than any other 

 natural group of living creatures, the explanation is 

 simple; they are and have been subjected to almost every 

 condition under which life is known to be possible. 

 Thus, to the entomologist, every difference of form, 

 colour, or attitude seems worthy of serious investigation. 

 He realises that an unusual tint or a quaint pattern carries 

 with it a definite meaning — that it is in some way linked 

 to the ancestral history of its possessor. Often enough 

 this meaning is mysterious. But occasionally the colours 

 and form of an insect, or of a group of insects, can be 

 explained as the direct outcome of certain known in- 

 fluences. Not infrequently such interpretations reveal 

 the fact that the shape or colour of an insect, or both in 

 combination, are mainly responsible for its well being. 

 The creature's peculiar appearance either mystifies its 

 enemies or enables it to approach unobserved the smaller 

 insects upon which it preys. The whole subject, to 

 which the general term " mimicry " is commonly applied, 

 constitutes one of the most fascinating phases of entomo- 

 logical study. 



The simple protective resemblance of an insect may 

 be either general or special. That is to say, the protec- 

 tion may originate in the mere likeness of an insect's sur- 

 face colouring to that of its customary surroundings, or 

 it may consist in an actual reproduction in both form and 

 colour of a certain object with which the creature is 

 commonly associated tliroughout its life. 



Instances of general protective resemblance must be 

 familiar to observers in all countries. The numerous 

 moths which are accustomed to rest for hours together 

 upon rocks or tree trunks are oft-cited examples. Con- 

 spicuous among tliem is the whole genus Calocala, the 

 various species of which are widely distributed in the 

 Pakvarctic region and elsewhere. These moths have 

 brightly coloured hind wings, the usual tint — which has 

 given to them their popular title of " Red-underwings " 

 — being some shade of crimson or pink. When they are 

 on the wing they are sufficiently conspicuous, and are 

 liable to be snapped up by a hungry bird. But when at 

 rest upon a tree trunk in tlieir customary attitude of 

 repose, the soft grey or brown colour of their fore wings 

 produces a general effect so well in keeping with the 



Catocala sp, Japan. 



Catocala sp. Japan. At rnst on bark. 



rough surface of the bark, that they are' extremely diffi- 

 cult to detect. Their colour pattern alone constitutes a 

 most effectual hiding. 



