( Ixxxii ) 



a progressive raising of the standard in both pursuer and 

 pursued. This is why it is that insects moan so much to the 

 naturalist or to the philosopher who desires to look beneath 

 the surface for the forces which have moulded existing forms 

 of life out of earlier and very different forms, 'fhe wings of 

 butterflies, it has been said, serve as a tablet on which Nature 

 writes the story of the modification of species.* But the 

 careful study of insects tells us even more than this ; for it 

 gives us the clearest insight we as yet possess into the forces 

 by which these changes have been brought about. Light is 

 thrown upon the causes to wiiich organic evolution is due no 

 less than upon the course which organic evolution has pursued.! 



And I think we shall find that a consideration of the 

 numerous distinct categories of forms presented by the insect 

 world is especially advantageous in an attack upon the diflicult 

 question — " What is a species 1 ", while properly-directed 

 observation of insects, and experiments upon insects afford 

 the most hopeful prospect of a final answer. 



And hei'e I am compelled to say a word in defence of the 

 Lepidoptera from this point of view. Undoubtedly it is most 

 unfortunate that the obvious attractions of the group have 

 led entomologists to neglect other Orders ; for this can be the 

 only explanation why natviralists have so often preferred to 

 do over again what others have done already, apparently 

 oblivious of fields comparatively empty and unexplored. It 

 must further be admitted, that the greater visibility of 

 structure, and the more iirgent necessity for the study 

 of structure in other groups, render them better instruments 

 of zoological education. But although the Lepidoptera are 

 inferior in this I'espect, although they lack the unique interest 

 of the Hvmenoptera and the social Neuroptera, and can- 

 not claim any of the respect due to venerable age like the 

 Aptera, Orthoptera and Xeuroptera — in spite of their mam- 

 demerits they stand at the head, not only of all insects, but 



* H. ^Y. Bates, quoted by A. R. "Wallace in "Natural Selection," 

 London, 1875, p. 132. The original passage may be found in "The 

 Xatuvalist on the Amazous" (London, pp. 347, 348 of the 1879 

 edition). 



+ This justification for the studj' of insects was m-gtd by the present 

 writer in the Hope Reports, vol. iii, 1903, preface, pp. 4, 5. 



