By Mary Margaret
THE small launch, with a quiet roar from the petrol engine, glided up a branch of the Sarawak River.The night was clear, the moon shone, and the stars sparkled.
Night travels up coastal rivers can be for several reasons, but visitors usually come to experience the wild — fireflies, crocodiles or both. And tonight we wanted to track fireflies.
Firefly light is beautiful and has inspired poets, myths and long lists of adjectives, metaphors and similes — firefly studded trees sparkle like diamonds, twinkle with lights, flicker like fairy lights, glisten like earth-bound stars .. They are beautiful, mysterious and diminishing.
We had come to drink in the beauty and to count the number of host trees along this single branch of the Sarawak River.
The mangrove nipah palm forest edged the smooth waters that inched to the South China Sea.
Individual trees hosted colonies of fireflies — some large and some small.
The lights were turned on as the sun fell over the horizon and darkness crept in.Fireflies are more likely to appear on dark moonless nights that are not windy (they are weak fliers). These insects are not flies, but winged beetles; members of the order Celeoptera and the family Lampyridae — which means torch bearer in Latin.
There are about 2,000 species of fireflies worldwide and 29 have been identified in Malaysia.
The major groups in Peninsular Malaysia are Pteropx, Luciola, Colophotia and Lychneuris.
Pteropx is the most widely distributed and is found in Peninsular Malaysia, Sarawak, Kalimantan and Thailand.
The fireflies we observed were identified as members of this group. Fireflies in this group have a synchronised light pattern that is displayed in host trees in mangrove nipah palm forest. And this is what we saw.
The firefly ‘lamp’ is located at the lower end of the abdomen and specialised cells in the light organ use oxygen to create the glow. The characteristics of the male light organ are used as a key indicator of species. Each species has a unique light pattern than includes variation in colour, time the light is left on, position on the crown of the host tree, on the ground or in flight. Some species have synchronised flashing and some do not.
Not all species of fireflies occur in large colonies along riverbanks, although these light displays are the most spectacular.
IN DANGER: Fireflies, despite their enchanting beauty, face threats on two main fronts — habitat loss and light pollution
These stunning light displays can become tourist attractions, like the famous display in Kuala Selangor in Peninsular Malaysia, which lures visitors from around the world.
Tragically this outstanding natural attraction is under threat as the forest along this section of the Selangor River is being cut down (‘Conservation Malaysia’, Issue N0 10 (2009).
The flickering and twinkling lights could be a mating call for the fireflies or perhaps a warning to predators that they are not tasty. The short-lived adults mate and die. In the wild they eat - they are voracious — but in the laboratory where they are fed with a sugar solution they can live for about two weeks.
The females, once they mate, fly inland to lay the eggs, which hatch in 15 to 20 days — in the soil, cracks and crevices, moss and decaying vegetation.
Fireflies spend most of their lives as carnivorous larvae consuming small snails and worms.
After several moults, an adult beetle emerges. In total, fireflies are thought to live four to seven months.
Fireflies, despite their enchanting beauty, face threats on two main fronts — habitat loss and light pollution.
They need dark nights and many species need forest cover for the display trees as well as for the eggs and larvae. The Pteroptyx species in Malaysia needs mangrove swamps.