Social insects, such as bees, ants, and wasps, utilize various communication methods to organize their societies. They regulate colony membership by discriminating nestmates from non-nestmates. In the face of this ”nestmate discrimination" system, social parasites employ diverse behavioral and chemical strategies to bypass their host's detection which result in successful exploitation of host labor and resources. In this study, we tested whether such parasitic adaptations could be detected in the incipient stage of social parasitism that is observed as an intraspecific phenomenon in some social insects. The Japanese parthenogenetic ant Pristomyrmex punctatus harbors a genetically distinct cheater lineage which infiltrates and exploits host colonies. This cheater lineage is found in multiple colonies and is thought to be horizontally transmitted between colonies. In each trial we introduced a cheater or a worker into a non-nestmate host colony to analyze her behavior and survival. We found that intrusion of the cheaters was effectively defended by host workers through nestmate discrimination without exhibiting any behavioral strategies specialized for social parasitism. Most of the cheaters were eliminated through aggression by host workers which are typically observed against non-nestmates, resulting in a low intrusion success rate for the cheaters (6.7%). This result contrasts with the expectation from interspecific social parasitism, which might be explained by the relatively short evolutionary history of the cheaters. We declare that this study has been published elsewhere (DOI:10.1111/eth.13533) for further details.