Tuesday, 4 May 2010

The Mundurra Balloon-winged Katydid

My friend Jack mentions each year the song of the Mundurra Balloon-winged Katydid, Hexacentrus mundurra Rentz, signals the end of the "beetle season" and the onset of the autumn period. This is true. But this year he notes that their raucous calls are not as prominent as usual. There may be ac couple of linked explanations for this. The continual wet period, which has been for more than 30 days now, may have promoted fungi which have reduced the populations. They are still around. You can hear them on warm humid nights.

These katydids are quite remarkable. While not true rainforest katydids, they occupy the rank grasses that grow along rainforest margins. Males sing by rubbing the forewings together. The sound if this species is so loud it can be heard from a moving vehicle with the windows down. It is a widespread species found across tropical Australia in woodland habitats. It lives close to the ground in dense grasses where it feeds on other insects--katydids a specialty. Neither sex can fly very well. Males glide a bit and females are generally flightless. What was interesting to me, and still is, is that this common, widespread and noisy insects had not been described until I named it in my monograph (Rentz, 2001). Maybe this is just an example of our state of knowledge of the Australian fauna, some 25% of which is named and the rest is, well left to the ages. And at the rate the habitat is changing and the direction of organizations like CSIRO are taking, it seems unlikely Australians will be describing these species anytime soon. It will probably be left to the Chinese to document our fauna!

Reference
Rentz, D. C. F. 2001. The Tettigoniidae of Australia. Volume 3. The Listroscelidinae, Tympanophorinae, Meconematinae and Mictotettigoniinae. CSIRO Publishing, Collingwood, Vic. 524 pp.

Female have an elongate ovipositor that they use to insert eggs into the ground in grassy areas. The following year the eggs hatch and the nymphs (hatchlings) are in just the right spot to take advantage of the small insects that live amongst developing grasses. Females are "dimorphic" for wing length. That is some individuals, like the one above, are fully capable of flight. Others are so short-winged that they can only glide.

This species is capable of delivering a very painful bite!

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