A recent reference:
 
Zeil, J. & Wittmann, D.  Visually controlled Station-Keeping by
   Hovering Guard Bees of Trigona (Tetragonisca) Angustula (Apidae,
Meliponae).  Journal of Comparative Physiology A 165:711-718.  1989.
 
   Author Address:  J. Zeil
                    Univ Tubingen, Lehrstuhl Biokybernet
                    Morgenstelle 28
                    D-7400 Tubingen 1  Fed Rep Ger