It is known that the Luciola parvula fireflies clearly emit the lights at regular time intervals and synchronization between multiple males are observed, but the details of synchronization have not yet been clarified. Presently, we took videos of the luminescence phenomenon of multiple male Luciola parvula fireflies and performed a correlation analysis on the details of the time change of the luminescence brightness of each male Luciola parvula fireflies. The 12 Luciola parvula fireflies are kept in glass wells so that each Luciola parvula fireflies can only moves in restricted areas and their luminescence is recorded by a digital movie camera at the video rate of 30 fps. According to the preliminary study, each glimmer lasts about 3 frames and thus the time series brightness is fitted by a parabolic function in order to give a precise timing of maximum brightness. First of all, time intervals between glimmers of each Luciola parvula fireflies are evaluated. Secondly, the glimmer correlation between different Luciola parvula fireflies are investigated. As a result, it was clarified that the light emission cycle of Luciola parvula fireflies is almost constant at 0.54 seconds, more than 70% of all light emissions are synchronized and the order of synchronization is almost fixed with very small delay. Consequently, it has been shown quantitatively that the glimmers of male Luciola parvula fireflies are well synchronized.
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