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PWS Public Safety Alert

16/01/2019

There has been considerable thunderstorm activity across the state overnight. Some fires have started in remote areas and the situation is being assessed as a matter of urgency.More

PWS Public Safety Update

16/01/2019

The Tasmania Parks and Wildlife Service is concentrating on its main priority - the safety of walkers and people in fire-affected parks and reserves.

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Gell River Fire update 14 January 2019 4.00 pm

15/01/2019

A fire is burning within the Franklin-Gordon Wild Rivers National Park, to the north of the Denison Range and through the Vale of Rasselas.More

Glow worms

Glow WormsGlow worms (Photo by Paul Flood)

Glow-worms (Arachnocampa tasmaniensis) are a spectacular underground sight. In some caves they cluster on walls and ceilings in their thousands—a myriad of blue lights resembling stars in the night sky. Being troglophiles, they also occur in moist, sheltered surface habitats such as rainforest gullies.

Glow-worms are not really worms, but the luminous larval stage of a fungus gnat. A chemical reaction in their abdomen produces a cold blue light. They are able to switch on and douse their lights at will. The larva builds a hollow, tubular nest of silk and mucous from which it suspends sticky threads up to 30 cm long. Flying insects, attracted to the lights, become trapped and are then eaten. In stream caves, the main insects caught are stoneflies, caddisflies and mayflies.

The aquatic, larval stages of these insects are carried underground by the stream. When they emerge from the water and metamorphose into adult flies, they are attracted up to the lights and become entangled in the sticky threads. Glow-worms quickly haul up the appropriate thread and consume their victim.

After several months of growth the glow-worm larva pupates inside a chrysalis, then emerges as an adult gnat. The adults live only a few days during which time they don’t feed—they have no functional mouth-parts. Instead, they mate. The female lays her eggs on the cave wall. Glow-worm colonies are dependent upon the continued availability of flying insects for their food,especially aquatic insects carried into caves by streams.

To preserve them it is important to maintain the natural conditions of stream flow and native forest within the cave catchment area. Glow-worms will stop glowing if people shine bright lights on them, or make loud noises. They are also disturbed by people passing close beneath them, and care must be taken not to brush or entangle the long threads.

Glow worms can be seen in the dense gully forest leading to Russell Falls at Mt Field National Park. In the north of the State, they are able to be seen in Marakoopa Cave, in the Mole Creek Karst National Park.