|Positive ||Menk ||On Dec 31, 2007, Menk from Darling Downs
This interesting and iconic insect is rarely encountered in the Australian bush. It is usually found at moderate to high elevation along the length of the Great Dividing Range, from near Herberton to Tasmania. It has also been found occasionally in pastures at relatively low altitude in western areas, as far west as Nyngan in NSW, and near Moonie and Chinchilla in Qld. It is known to inhabit the Carnarvon Ranges.
In SE Qld the species prefers Themeda triandra (kangaroo grass) grasslands in open eucalypt and grasstree forest, often above elevations supporting rainforest or vineforest. It is often found above cliff lines and near rocky scree slopes. Further west it may be found in hilly wooded country, only rarely on the plains. It can sometimes be locally common, but is most often encountered as isolated individuals. The females are the most commonly seen.
The photos by kennedyh show the male of the species which has wings. The female has no wings, only small wing covers which are grey and crinkly and look like half peanut shells.
I have included some photos here of the female. Unlike the male, the female does not look much like a grasshopper. She is dumpy and has long, spidery legs that seem out of proportion with her large body. When disturbed, she lifts her wing covers and arcs her body to expose the bright red and blue stripes on her back and the bright orange collar around her neck. She may do a kind of dance when disturbed, standing right up on her thin legs, and moving around in half circles, or in a kind of staggery manner. They are completely harmless and all bluff, but I am sure some people have mistaken them for wasps, spiders, or hornets. I hope to include some more photos in future, showing the remarkable defense posture of the female. The males also have a defensive pose, involving flaring of their wings, strutting, and arching of their body. Their abdomen is also bright coloured.
The female katydid is mute. The male mountain katydid calls in the early morning and from late afternoon to just after dark. Their calls vary from time to time, from population to population and within populations. Sometimes it is a bit like soft yet rapid machine gun fire. The call is typically one long burst, followed by two shorter bursts, with the final burst often cut off abruptly. However the most typical katydid calls I have noted are of two kinds: one is what I call the "courtship call", which is shrill and cicada-like. Unlike a cicada though, the sound is not sustained and cuts off after a short while. The other sound is what I call a "territorial scolding". The males do this whenever a potential predator gets close by. No doubt they perceive threats in footsteps, shadows, and even the wind can cause them to make this call. It can be described as a short sharp "chip" sound, often repeated two or more times. I believe it serves as a warning to the ground-dwelling females. I have noticed that whenever the males make this sound in captivity, the females stop dead in their tracks, as if frozen in place. They start moving again a few seconds later.
Occasionally males will produce a single, low-pitched ascending or descending, almost "guttural-sounding" call. But I am unsure about the relevance of this call. It is commonly heard in the early morning or late evening as one of the first calls produced. Perhaps it is a kind of aggressive or intimidating call intended towards other males in the area... or it may simply represent a form of "warming up". I am not sure. Young males are more likely to make this sound before they are capable of producing the complete courtship sound. So maybe these calls just represent miscellaneous "practise" sounds.
The males occasionally call throughout the day, generally resting head down on a low branch in a prickly bush to avoid detection. The male is generally reluctant to fly, but if disturbed can fly 10-20 metres, before dropping into another bush. In cool or cloudy weather, the male may rest motionless on the ground, and look just like a fallen leaf. As with the females, it too is fond of basking in sunny spots.
It is thought that the males have poorly defined territories within a kind of clan or colony, in which a small "harem" of ground-dwelling females roam. But little is known about the dynamics or social structure of their colonies. In captivity, the females often seem to be attracted to the male's call, which may serve to keep them within a certain range. At the same time, the ground dwelling females, though mute, may be constantly seeking out new food sources. The male will sometimes chirp as if in alarm when a potential predator comes nearby. It is likely that the entire colony migrates gradually in search of new feeding grounds, as they deplete their food sources.
I have estimated that their territories may cover about a 10-30 metre radius. Males probably compete with other males for mates. The females large abdomen supports large numbers of eggs. They always lay their eggs (which are beige coloured and the size and shape of Acacia seed) well away from their host plants, and in a spot where fire cannot reach eg. around rock scree, overhangs, or in rainforest. They never lay all of their eggs in one place, but distribute them over a wide area.
I have only recently discovered that they often lay their eggs in the topsoil. They dig a small hole, lay the eggs, then carefully bury them and smooth the surface off meticulously with their tiny feet. Each female is capable of laying dozens of eggs in her lifetime. The eggs can take many months, possibly even years to hatch, waiting until conditions are just right. Only a small number of the ant-like young (called nymphs) will ever make it to adulthood. Other females have been observed depositing their eggs on low grasses and sticks.
It is vital to preserve these insects in Australia, not only because they are an iconic species, but because they may serve a valuable economic purpose. Their favourite food source is Asteraceae (the daisy family), with a preference for the more weedy species. They love fireweeds. They will eat off the flowers, leaves and buds, and even the seeds, of these plants. Both the native fireweed Senecio lautus, and the troublesome exotic Senecio madagascariensis are high on their menu.
The introduced ragwort pest, Senecio jacobaea, is one of their favourite foods, however captive specimens have shown an intolerance towards this species. In some cases deaths have been attributed to consumption of S. jacobaea in captivity. They will also eat many of the native Senecio species, as well as Leiocarpa species (Billy Buttons) and probably the common Chysocephalum apiculatum. They also love Achillea milleflorum and A. distans (yarrowherb). I once observed a female katydid consume an entire yarrow leaf in five minutes flat!
They have also been observed eating the leaves of blue heliotrope weed (Lamium amplexicaule), which is a common weed, however most captive specimens have quickly shown symptoms of toxic poisoning and some have even suffered death after being fed this plant.
Unfortunately this species has gone into dramatic decline in recent decades. Loss of habitat due to development and weeds (Lantana camara in particular) is largely responsible. Introduced fauna (mice, rats, cats, foxes, cane toads) have almost certainly taken a heavy toll as well. They love to bask in the early morning sun, so they may venture on to walking tracks in national parks. They may even stroll on to suburban lawns that are located near large forest areas. When walking at high elevations it always pays to watch where you are treading. I strongly suspect that some introduced weeds which may be palatable to this insect, may also be poisoning them.
It is vital to preserve large areas of natural Themeda grasslands, particularly those on the Dividing Range in open eucalypt forest. This is a community on which the Acripeza largely depends in Queensland. In southern states, they may rely on Poa grasslands.
It is probable that the introduced ragwort had smothered out the native Senecio species, and even though it provided an excellent surrogate food source for the katydid in the early days, problems associated with toxicity caused a decline in the katydid population. Drought and introduced predators have further hindered their recovery. It seems likely that they have become extinct from large areas where they were once common.
The only safe exotic plants that can be fed to the mountain katydid are the two Achillea species mentioned previously, and Heliotropium indicum.
The native plants that the mountain katydid eats, such as Senecio lautus, may be unpalatable or potentially toxic to other animals. It is thought that the katydid has the ability to store these toxins in its own body tissues, making it untasty if grabbed by a predator. Still many do succumb to predation. Magpies have been observed eating them. Some birds and lizards may be able to cope with the toxins or have perhaps learnt to eat only selective parts of the insect . I suspect that many of the feral animals, like cats, may kill these insects out of instinct or curiosity, even if they find them distasteful. Cane toads may prove to be a major predator, but more study is needed. Ants are also a substantial predator of the katydid when they swarm during hot weather in summer. The females are particularly vulnerable to attacks by swarms of ants.
Apart from their bluff response and the toxins stored within their tissues, the mountain katydid is completely harmless. Needless to say it is impossible for this katydid to transfer any toxins to humans through the process of handling. Never has there been a more harmless and remarkable insect!