A horned beetle which fights

Abstract

HORNS, and other often elaborate forms of prothoracic and cephalic armature, are a well known feature of male and occasionally female beetles in the family Scarabaeidae (Coleoptera)¹. Many of these, including rhinoceros beetles (Dynastinae) and dung beetles (Scarabaeinae, Geotrupinae), have been studied in detail, but the function of the horns is still the subject of dispute². The idea that in certain circumstances it would be an advantage for male insects to fight for the possession of a female or a breeding site, and that horns and similar appendages have evolved as weapons, has recently been put forward by Hamilton³. The male of the geotrupine Typhoeus typhoeus (L.) is well armed in this way (Fig. 1), and the observations that I report here show for the first time in a burrowing beetle, not only that the horns are used for fighting between males, but that they are specifically designed for the purpose.