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Psyche 
[Vol. 95 
to the larval cuticle (Isingrini et al. 1985) or coloured spots of paint 
applied to cocoons (R. J. Stuart, personal communication)]. Other 
techniques, although effective, are not efficient in terms of the time 
required to obtain marked larvae. For example, Brian & Rigby 
(1978) and Cole (1981) report that Sudan black, an oil soluble dye, 
fed to a queen results in the production of coloured eggs. Appar- 
ently, this mark is retained through all life stages including adult- 
hood (R. J. Stuart, personal communication). For the purposes of 
our experiments, waiting for dye to be ingested by the queen and for 
the marked eggs to develop into larvae was inefficient. 
Adult ants are known to devour even slightly damaged brood 
rapidly and to regurgitate this material to healthy larvae (Wilson, 
1971). Thus it seems plausible that if a coloured substance is applied 
externally to brood that causes workers to perceive marked brood 
as damaged, the coloured substance will end up inside healthy lar- 
vae in the colony. Such a mark would be visible to a human 
observer through the translucent larval cuticle, and if effective 
would provide a rapid and inexpensive means of marking large 
numbers of larvae. Here I describe a technique for obtaining 
marked larvae, present data on the persistence of the mark, and 
demonstrate that marking does not bias larva acceptance by Lepto- 
thorax ambiguus or L. longispinosus workers. 
Methods and Materials 
Nests of both L. ambiguus and L. longispinosus were collected 
during September, October and November 1985 and from April 
through July 1986 at various sites within the regional municipalities 
of Halton and Peel, Ontario, Canada. Ant colonies were cultured in 
the laboratory employing techniques described by Alloway (1979) 
and Hare (1987). 
In a pilot study, 10 larvae smeared with Testor’s red enamel paint 
(#1150, commonly used to paint plastic models and available at 
local hobby retailers) were placed inside the nest of each of 17 L. 
longispinosus colonies. Within 24 h, 5 to 10 (8.5+1.87 [mean + SE]) 
of those larvae were cannibalized by adult workers. During this 24 h 
period, trophallactic exchange of food from workers to previously 
unmarked larvae resulted in a large proportion (0.63 + 0.17 
[mean + SE]) of each colony’s larvae becoming marked internally 
