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Psyche 
[Vol. 89 
pendently. The parasite queen finds a colony of her host species, 
enters it, and somehow usurps the role of a host-species queen. The 
host-species workers then raise the parasite queen’s brood. 
Species of temporary parasites possess a completely functional 
worker caste. At first, the temporary-parasite workers and the host- 
species workers exist alongside one another. However, when the 
host-species workers die, they are not replaced; and a pure colony of 
the temporary-parasite species develops. The workers of slave- 
making parasites are highly specialized for fighting and raiding the 
nests of host-species colonies; and as a consequence of their raids 
during which they capture host-species worker pupae and larvae, a 
force of host-species workers (or “slaves”) is maintained. Inquiline 
parasites either have no worker caste at all; or, if one is present, the 
workers seem to play no role in maintaining the colony. In some 
cases, a continuing supply of host-species workers is maintained by 
the host-species queen’s coexisting with the inquiline queen (Busch- 
inger, 1970; Wilson, 1971). 
This paper presents data concerning several aspects of the behav- 
ioral biology of three North American species of the ant genus 
Leptothorax Mayr: L. ambiguus Emery, L. curvispinosus Mayr, 
and L. longispinosus Roger. These species interested us because 
they are hosts to three closely related parasite species. All three 
species are enslaved by the obligatory slave-makers L. duloticus 
Wesson and Harpagoxenus americanus (Emery); and L. curvispino- 
sus is the host of the workerless inquiline species L. minutissimus M. 
R. Smith (Alloway, 1979; Creighton, 1950). Thus, studies of the 
behavior and ecology of these three nonparasitic species may eluci- 
date the ethological and ecological circumstances under which 
social parasitism evolves and is maintained. 
Number of Queens and the Sex of Broods in Nests 
Headley (1943) and Talbot (1957) reported that the number of 
queens in nests of L. curvispinosus and L. longispinosus is quite 
variable. Some nests contain several dealate queens, some contain 
one, and some contain none at all. Observations indicated that the 
number of queens in nests of L. ambiguus is also variable (Alloway, 
unpublished data). In addition, we found that many queenless nests 
of all three species contained broods which either included worker 
and queen pupae at the time of collection or matured into worker 
and queen (as well as male) pupae. 
