Synchronous flashing of a large congregation of fireflies observed at
Varagaliar, located in the Anamalai Tiger Reserve in the Tamil Nadu part of Western
Ghats (10°25.09' N, 76°51.94' E, Elevation 2100 ft) is reported here. Typically, the
fireflies on the topmost part of the tree crown flash a yellowish green light, almost
immediately followed by similar light flashes serially by the fireflies below. The
flashing pattern in each tree repeated itself cyclically, and other neighbouring trees had
similar but unique synchronous displays. After a few cycles, fireflies in all the trees
flash three times in unison as if appreciating their spectacular performance. The whole
forest landscape resonated with pulsating waves of multiple kaleidoscopic flashes of
light from several clusters of fireflies until dawn. This annual spectacle is observed only
during the month of April, before the onset of the south-west monsoon, perhaps
coinciding with the mating season of the adult insect that lives for about a month.
Synchronous fireflies have also been reported elsewhere from Southeast Asia, the Great
Smoky Mountains National Park, Elkmont, USA, and Brazil. Conserving this unique
phenomenon at Varagaliar for posterity, necessitates a better understanding of the
species composition of the fireflies involved in this phenomenon, the reasons for their
synchronous behaviour, the geographical area that is congregated by these insects, the
unique plant species composition, and the ecology and ecoclimate of this habitat that
makes it an exclusive niche for congregation of synchronous fireflies.
Keywords: Anamalai, annual spectacle, conservation, cyclic, ecotourism, glow
worms, mating, monsoon, synchronous fireflies, vegetation, Western Ghats.
