I9K3] Alloway & Del Rio Pesado — Harpagoxenus 431 
move them from nest to nest in polydomous colonies. Nevertheless, 
H. aniericanus workers possess certain vestiges of non-parasitic 
behavior. Inside their nest, H. aniericanus workers routinely groom 
one another, periodically share regurgitated food with other slave- 
makers and slaves, and occasionally engage in what appears to be 
brood care. Parasite workers may even eat if they encounter food 
while scouting. On such occasions, one can infer that the slave- 
maker is scouting (and not foraging) from the fact that, after eating, 
it continues to “look for” a target nest, instead of returning directly 
to its own nest, regurgitating to nestmates, and recruiting them to 
the food source. H. aniericanus workers never recruit or follow 
nestmates except in the context of slave raids. 
Although Leptothorax slaves generally look after the slave- 
makers, we observed many instances of slave aggression against 
slave-makers. In 9 slave-maker colonies, we saw slaves biting and 
dragging H. aniericanus workers out of slave-maker nests. A few H. 
aniericanus workers lost parts of appendages as a result of these 
attacks. However, we never saw a slave-maker attack a slave; and 
we never witnessed anything resembling a generalized “slave revolt”. 
Individual H. aniericanus workers were attacked by individual 
slaves. The same slave which attacked one slave-maker would feed 
and groom another; and any slave-maker that was attacked by one 
slave was cared for by others. 
A somewhat different kind of slave aggresssion was seen in one of 
our incipient H. aniericanus colonies. When collected, this colony 
possessed a single nest containing an H. aniericanus queen, 17 L. 
longispinosus workers, and a brood. Throughout the course of our 
observations, the slaves fed and groomed the parasite queen and 
tended her brood through the pupal instar. However, the slaves 
killed all eclosing H. aniericanus workers. Similar events have been 
observed in other incipient H. aniericanus colonies (R. J. Stuart, 
personal communication). 
As we have noted, slaves ordinarily defend the area surrounding 
H. aniericanus nests against incursions by unenslaved Leptothorax 
workers. Similarly, unenslaved leptothorax workers defend areas 
around their nests against incursions by Leptothorax slaves. These 
phenomena, together with the fact that both enslaved and unen- 
slaved Leptothorax workers fight for their respective colonies during 
slave raids, indicate that enslaved and unenslaved Leptothorax 
workers generally recognize one another as belonging to different 
