Males of the cicada Okanagana rimosa emit acoustic signals that attract sexually receptive conspecific females. This acoustic signal is also used by females of the parasitoid fly Emblemasoma auditrix to home in on the cicada and infest it with larvae. In a field study we investigated factors influencing the phonotactic behaviour of the fly by attracting them to broadcasted natural and artificial acoustic signals. The success of attraction depended on weather conditions and was best in sunny conditions with temperatures above 25 C. Attraction of flies correlates with that of female cicadas, indicating that both have the same preferences. By varying parameters found in the natural calling song, we showed that frequencies and rhythm patterns which closely resemble the host signal were most attractive. Female cicadas also responded to the signals sooner and arrived earlier at the loudspeaker (median latency 16 seconds) than the first fly (median latency 35 seconds), perhaps an adaptive behaviour to the parasitism. The behaviourla auditory threshold intensity of E. auditrix was around 70dB SPL.