306 
Psyche 
[Vol. 95 
longispinosus showed a preference on any day for marked or 
unmarked larvae. Furthermore, ants placed marked and unmarked 
larvae in a common brood pile within the nest. Thus the presence or 
absence of the mark itself did not influence larva-acceptance by 
Leptothorax. 
Throughout the course of the experiment, deviations from equiv- 
alent numbers of marked and unmarked larvae accepted typically 
were in the direction of a greater number of marked larvae within 
both species. However, those deviations were quite small. The 
explanation for this pattern lies in the observed tendency of Lepto- 
thorax workers to prefer large larvae (Hare 1987). Whenever larvae 
were marked, it appeared that large larvae became marked more 
readily than small larvae. This in itself suggests that large larvae 
receive preferential treatment (in terms of regurgitation from adults) 
in their maternal colonies and results in uneven size distributions of 
marked and unmarked larvae. In spite of efforts to match larvae as 
closely as possible on the basis of size, marked larvae were often 
slightly larger than the unmarked larvae used, thus explaining any 
apparent trend towards preferential acceptance of marked larvae. 
Summary 
A technique is described whereby a visually observable mark can 
be transmitted to the gut contents of ant larvae. The technique is 
inexpensive, provides large numbers of marked larvae on demand, 
and is useful in situations requiring a mark duration of less than 10 
days. Results of a choice experiment demonstrate that the mark 
itself does not bias larva acceptance by Leptothorax workers. 
Acknowledgments 
Funding for this research was provided by the Natural Sciences 
and Engineering Research Council of Canada in the form of a grant 
to T. M. Alloway and a post-graduate scholarship to J. F. Hare. I 
thank Lew Holowaty, Andrew Kajioka, Alikeshs Leighl and Roger 
Mosquera for technical assistance and T. M. Alloway and R. J. 
Stuart for enlightening discussions during the development of this 
technique. I also thank Karl Larsen, R. B. MacWhirter, J. O. Murie 
and P. J. Young for helpful comments on earlier drafts of this 
manuscript. 
