Stridulation, a form of acoustic communication, is an important yet poorly studied component of ant communication. Although many ants are capable of stridulation (Markl 1973), little is known of the behavioral implications of this signal. The leaf-cutting ant, Atta cephalotes, is the only well studied species where the behavioral role of stridulation was investigated. Markl (1965) observed workers dig out buried nest mates, when buried workers were stridulating. Similarly when workers encountered good quality leaves, they stridulated to recruit nearby nest mates (Roces et al. 1993). Stridulation has been observed in both the red and black imported fire ant (S. invicta and S. richteri, respectively), but little is known of the behavioral implications of these signals. Preliminary results suggest that S. invicta and S. richteri stridulate from a variety of different cues: nest disturbance, discovery of a new food source, physical restraint, and interactions with ants of intra or interspecific colonies. Recordings of the acoustic signal with corresponding real-time video of the stridulating ants and surrounding nestmates will provide evidence of the role of stridulation in the behavior of S. invicta and S. richteri. This approach will also be used to investigate the interspecific difference of the stridulatory signals between S. invicta, S. richteri and their hybrid (S. invicta/richteri). Intraspecific differences of stridulatory morphology and acoustic signals will also be investigated in the polymorphic worker caste of both species.