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After Luciola praeusta Kiesenwetter 1874, Asymmetricata circumdata (Motschulsky) is the second Indian species of firefly identified recently. Here we present steady-state and time-resolved measurements of bioluminescence emissions of male specimens of this new-found species. Steady-state spectra recorded in a high-resolution spectrometer show the peak wavelength at 570 nm, while the same on a colour film in a glass spectrograph show the peak at 579 nm between green and red bands, which prompts speculation that a sharp, laser-like line might exist in the emission spectrum of this species just as the one in L. praeusta. The diffraction pattern produced by a grating consolidates this proposition. Flashes recorded in an oscilloscope reveal the appearance of a small pulse in combination with the main one, which becomes prominent both at low and high temperatures.

Bioluminescence emissions from a few species of fireflies have been studied at different temperatures. Variations in the flash-duration have been observed and interesting conclusions drawn in those studies. Here we investigate steady-state and pulsed emissions from male specimens of the Indian species Sclerotia substriata at temperatures considerably higher and lower than the ones at which they normally flash. When the temperature is raised to 34 °C, the peak wavelength gets red-shifted and the emitted pulses become the narrowest which broaden considerably thereafter for small increases in temperature; this probably indicates denaturation of the enzyme luciferase catalyzing the light-producing reaction. When the temperature is decreased to the region of 10.5–9 °C, the peak gets blue-shifted and the flash-duration increased abnormally with large fluctuation; this possibly implies cold denaturation of the luciferase. We conclude that the first or hot effect is very likely to be the reason of the species being dark-active on hot days, and the second or cold one is the probable reason for its disappearance at the onset of the winter. Our study makes the inference that these two happenings determine the temperature-tolerance, which plays a major role in the selection of the habitat for the firefly.