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ON THE SUPPOSED NUMERICAL PREPONDERANCE 

 OF THE MALES IN ODONATA. 



By R. J. TiLLYARD, B.A. 



Those entomologists who have paid any attention to the 

 " Odonata," or Dragonflies, have all agreed in stating that the 

 males outnumber the females very considerably in most, if not in 

 all, of the species. It is not necessary here to give a lengthy list 

 of quotations from European or American authors who have made 

 this observation; it is sufficient to quote M. Rene Martin, one of 

 the very best authorities on the Odonata, and one who has an 

 extensive knowledge of many of our Australian species. Speaking 

 of Xanthagrion erythroneurum, one of the Australian Agrionidce, 

 he says, "Les males semblent etre plus nombreux que les femelles; 

 ce qui est un cas frequent chez beaucoup d'especes d'Odonates.""^ 

 The statement can be well borne out by anyone who will take the 

 trouble to examine any extensive collection of Odonata from any 

 part of the world. It is generally found that in collections the 

 males outnumber the females by nearly two to one. One may 

 well doubt, however, that Nature has struck such an uneven 

 balance between the sexes. In this paper I shall endeavour to 

 set out the reasons which have led to the prevailing view, and to 

 show that in reality it is not the case, but that the numbers of 

 the sexes are approximately equal. 



My own collection, made in New South Wales and Queensland 

 during the past season, is no exception to the general rule. 



* A List of Dragonflies of Australia : J. G. 0. Tepper; annotated by M. 

 Een6 Martin. 



