Hudson. — N .Z. Insects illustrating Principle of Sexual Selection. 431 



Art. XXXVI. — On some Examples of New Zealand Insects illustrating 

 the Darwinian Principle of Sexual Selection. 



By G. V. ituDSON, F.E.S., F.N.Z.Inst. 



[Read before the Wellington Philosophical Society, 24th September, 1919 ; received by 

 Editor, 31st December, 1919 ; issued separately, 16th July, 1920.] 



Notwithstanding constant attempts to refute or profoundly modify 

 Darwin's theory of natural selection, or the " survival of the fittest," it 

 cannot be denied that this theory remains to this day the only satisfactory 

 explanation of the innumerable instances of adaptation to conditions which 

 are manifest to the most casual observer of plants and animals. It is 

 not, however, my intention this evening to give instances of the operation 

 of natural selection amongst our New Zealand insects, although practi- 

 cally every species might be utilized in corroboration of Darwin's great 

 theory. My object on this occasion is to direct attention to Darwin's 

 subsidiary theory of sexual selection, which some of his immediate fol- 

 lowers were convinced had been a most potent factor in the evolution 

 of the more advanced attributes of the higher animals, but which has 

 unaccountably been allowed to drop into the background by many present- 

 day biologists. Some may perhaps urge that the theory of sexual selection, 

 as propomided by Darwin in his Descent oj Man, is an out-of-date doctrine, 

 superseded by more precise modem researches into the minute structure of 

 organisms. Before, however, any such general statement can be accepted 

 a more complete explanation than that afforded by sexual selection must 

 be given of the actual facts existing in nature, and this I think I can 

 safely say has not yet been done. Without further preliminaries I will 

 now direct attention to a few of the facts referred to, and will use our 

 New Zealand insects in illustration of my remarks. 



1. Order Hemiptera. Suborder Homoptera. 



The suborder Homoptera includes the cicadas, lantern-flies, and their 

 allies, as well as the aphides, scale insects, &c. 



The family Cicadidae, often popularly known as " locusts " or " singers," 

 the first name being most misleading, is one of the best-known families 

 of New Zealand insects. We have upwards of a dozen species, of 

 which the largest, Melamjnalta cingulata is often extremely abundant in 

 the late summer. At this season the singing of the males, as they rest on 

 the branches of trees and shrubs, is sometimes almost deafening, and the 

 noise may be best likened to that produced by a number of frying-pans 

 simultaneously in operation on a very hot fire. This sound is produced 

 by two complicated organs connected with the respiratory system of the 

 male, and situated on the underside of the base of the abdomen. It is 

 solely confined to that sex. The singing is undoubtedly attractive to 

 the female, and close observation of the insects in their natural haunts 

 often discloses the fact that the keenest rivalry exists belrween two or more 

 males to . captivate a female by means of their music. It is impossible 

 to assign any other use to these complicated organs, and the instmct to 

 use them, than that here indicated. The sound emitted certainly does 

 not intimidate the enemies of the cicada, as they are all much preyed 



