The distribution, life cycle and flash behaviour of the firefly Pyrocoelia praetexta Olivier (Coleoptera: Lampyridae) in the Alishan area of Taiwan

Abstract

The firefly Pyrocoelia praetexta Olivier is abundant in the Alishan area in Taiwan. The vertical extent of the Alishan area ranges from 400–1500 m above sea level. Sixteen species of terrestrial snails, including eight new records (Cyclophorus taivanus, Cyclophorus formosensis, Ptychopoma wilsoni, Coniglobus nux, Coniglobus arisana, Aegista subchinensis, Aegista (Plectotropis) impexa, and Pancala batanica pancala), have been identified as prey of this firefly. From September to December late instar larvae of fireflies were found preparing for pupation and many flashing males were observed, with the peak being from October to December, depending on the elevation. Two basic life cycles of P. praetexta were observed. Type I is univoltine with overwintering eggs and type II is bivoltine with larvae. It was found that at higher elevations (1200-1500 m) the adults emerged earlier than adults at the lower elevation of 400 m. The average body length of an adult firefly at the higher mountain elevations was significantly larger than that of an adult firefly in the lower mountain elevations (p< 0.01). The imaginal period lasted from September to October. Maps of the vertical distribution of P. praetexta were plotted using the geographical information system and showed that distribution is related to elevation and local flora of the Alishan area. The male photic emission was 525.2–590.8 nm, with the emitted peak wavelength λmax at 547.44 nm. Conservation problems and firefly watching activities in the Alishan area are also discussed.