Enhancing conservation of the Tasmanian glow-worm, Arachnocampa tasmaniensis Ferguson (Diptera: Keroplatidae) by monitoring seasonal changes in light displays and life stages

The light displays by the Tasmanian Glow-worm, Arachnocampa tasmaniensis Ferguson (Diptera: Keroplatidae), in Exit and Mystery Creek caves in southeast Tasmania, Australia have been recognised as a world heritage value under the criterion relating to outstanding natural phenomena. To conserve and manage these populations, particularly in response to potential tourism development, a better understanding of their ecology is needed. Aspects of the life cycle of A. tasmaniensis were monitored over 24 months. A strong seasonal pattern was found, with pupae and adults most common in spring and summer. The increase in numbers of pupae and adults coincided with an increase in the number of prey caught in silk threads produced by the larvae. Larvae were present throughout the year but the number glowing varied both seasonally and spatially. In Mystery Creek Cave, the number of larvae glowing was generally highest during summer and autumn and lowest in winter and early spring. In Exit Cave, there was no consistent seasonal pattern in the number of larvae glowing among sites, and overall there was less variation between monthly counts than at Mystery Creek Cave. This difference in seasonal patterns between the two caves may be due to a difference in climate, with Mystery Creek Cave possibly experiencing a greater drying out of the cave air in winter than Exit Cave.