On the other hand, the lack of active movement caused by decapitation significantly prolonged the courtship latency when there was no visual information, suggesting that active movement of both intact and wingless females helped the male to notice the target female. When visual cues are available, males easily find the decapitated silent female, suggesting that the strong positive cue provided by the visual system overcame the lack of female movement. One possible way in which female activity could enhance initiation is if chemicals released by active females and distributed in the chamber allowed males to use gustatory sensation to ����taste���� the female��s footprints. To test this, we pre-scented the chamber with three active females, but this did not decrease courtship latency toward a decapitated immobile female. It is clear that olfaction is extremely important in initiation in the dark, but these experiments rule out a chemosensory cue as being an explanation for the difference in initiation of courtship toward mobile and immobile targets. How does female movement stimulate courtship initiation? Does it work as a navigator to help the male to locate the XAV939 Wnt/beta-catenin inhibitor position of the female? Or is it a trigger, which alerts the male to the potential presence of the female, stimulating some sort of searching behavior? In order to assess these possibilities, we provided ����fly sounds���� to the male in the presence of a decapitated female by placing the courtship chamber over a speaker and replaying a recoding of flies walking around in a chamber. If mechanical stimuli trigger searching, this noise should stimulate courtship initiation. On the other hand, if the test male employs the movement noise of a female to position and/or chase her, noise played through a speaker won��t rescue the delayed courtship initiation toward a silent female and might even disrupt the test male��s ability to locate the position of the real target female. We found that fly noise enhanced courtship initiation, causing the mean latency of courtship toward a silent female to be significantly shorter than with a silent female alone. The courtship latency toward a decapitated immobile female paired with fly sound was even shorter than that with a mobile female. Courtship initiation was enhanced also by addition of a wingless noise maker male into a chamber, implying that both males and females can emit non-sex-specific mechanosensory signals that alert a male to the presence of another animal in AMN107 side effects proximity and stimulates him to search for a female in a large field. The ability of fly sound to stimulate the male to look for a female could reflect either a specific recognition of ����fly sounds���� or an alteration in the male��s attentional state.