DIMORPHISM IN HALlCTINE BEES 



(Digr;t of Presidential Address by Taxltox Eaymkxt, i .i».z .s., 

 delivered to the b'.N.C.V. m May 1956) 



For over rhuty yeai s 1 have been studying certain small fGssbnaJ 

 f>ees known as Halictns, and the complexity 01 their biology intrigues 

 utc today even more than it did when J discovered my first colony. 

 Die &CCti are smul! in stature* a hour six or eight millimetres in 

 length, hut the group that has held my unlading interest throughout 

 the years is comprised ot the highly coloured metallic specks tailing 

 within the subgenus Chloral iff us (i e ^coloured Hulictux)- 



And what delightful lirlle gems, they are ! Most have a green head 

 Mn.cl thorax atjd art apricot-coloured abdomen, On several the head is 

 almost black, but others ivill he So magnificently iridescent On the 

 thorax that even the most hery ojials cannot excel the hnlhance o( 

 their colour. The abdomen, too, is no fefs surprising in us range of 

 colours, many have the rich dark castan eons-red of the chestnut, 

 Ijui Ike majority match the clear orange tints of the aprkut: one r>r 

 two are cadmium, verging on yellow. Whatever their tints may b<?, 

 the bees are exquisite gems. 



1 made my first acquaintance with rhese chloraliccinc bees m the 

 sand) eastern shore of Porr Phillip, when die hilled nl Ihe sen : md 

 of the sky were. perfectly itansluoeivi. and ihe Stlna rays were tem- 

 pered by the breeze from the sea. ... Ii was a day for the gods to 

 dream- So I ( too, fell ur.dCT the spell of Mother Nature, but I did not 

 dream. 



Presently my eyes focussed on a small black ant carrying some 

 thing on its back; il was a slued of withered golden leal. Right 

 before my startled ga/.e, a minute polished black insect 'shot out of 

 the ether 1 ' and attempted to male with the ant, My natural history 

 told me something unusual was- .doot. My net cut ,hc air,, and I had 

 both insects imprisoned in its meshes'. 



Now 1 can examine rhcrn inticatly under a lens. Yes. a small 

 black worker anr, known to everybody, and the other, an even 

 smaller halictme bee. not known to anybody 1 (l-ater, mv revered 

 mentor and friend, Professor Coekerell, dedicated the species a? 

 Cft to* -a tict ps raymenfi Ckll.] For several years afterwards, I spent 

 hour? in rhat locality, searching for a black female to correspond 

 with Ihe tiny male. 1 never found one, Imr iu due time I did discover 

 a colony of the bees, and also the cause of my forgivable error. You 

 see> every one of the females, and there were hundreds of them, had 

 a mclajliogrccn head and rhorax and an apricot-coloured abdomen. 

 And what of the males? There were hundreds of them. loo r but all 

 were jcr-black and polished 1 have dissected perhaps thousands nt 

 Haticti and 1 am sure, of my facts. 



■ I did discover then the explanation of the initial phenomenon will) 

 the am. In the sunlight, the piece oi yellow leaf, thrown over its 



