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DISPLAYING POSTS TAGGED: prickly katydid (1)

Bug of the Month - Prickly Katydid

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by Patrick
Publish date
1 January 2012
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Prickly Katydids, or Spiny Tree Crickets, occur from the rainforests of northern New South Wales to Iron Range in Far North Queensland. There are four species of Prickly Katydids but the most common is Phricta spinosa. It has the rather long official common name of Giant Spiny Forest Katydid and is found from Innisfail to Cooktown. Those that know and love this species simply call it Phricta.

Prickly Katydid. The spiny countenance of a Prickly Katydid.
Image: Patrick Honan
Source: Patrick Honan
 

During the day, Phricta sits motionless on bark or amongst twigs with its legs held out straight where it is remarkably well camouflaged. Some bird species, particularly Black Butcherbirds, move up and down tree trunks trying to disturb the insects so they will give themselves away. When threatened, Phricta will point its back legs skyward, revealing rows of sharp spines and red patches at the bases of the legs. These red patches appear to discourage predators.

adult male prickly katydid The legs of this adult male bear the black and orange markings of its startle display.
Image: Patrick Honan
Source: Patrick Honan

Adults have a body length of 10cm or so, and their highly sensitive antennae may be three times that length. Adults are normally found high in the rainforest canopy, but after mating, the female glides to the ground to lay her eggs in the soil.

Prickly Katydid laying eggs An adult female pushes her abdomen into sandy soil to deposit a batch of eggs
Image: Patrick Honan
Source: Patrick Honan
 

The young Phricta feed low in the understorey on the constant 'rain' of flowers and buds from above.

A young nymph feeding on a fallen flower bud. A young nymph feeding on a fallen flower bud.
Image: Patrick Honan
Source: Patrick Honan

Phricta moult several times before reaching adulthood. Moulting takes place during the first part of the night and they are very vulnerable to predators at this time. The elongated antennae may take a long time to withdraw fully from the old skin.

Phricta moulting at night. Phricta moulting at night.
Image: Patrick Honan
Source: Patrick Honan
 

The colours of juvenile Phricta are variable and help camouflage them against tree trunks and lichen-covered bark.


Juvenile prickly katydid Juvenile Phricta are often beautifully patterned with greens and browns. The budding wing pads can be seen between the spines of the legs and thorax.
Image: Patrick Honan
Source: Patrick Honan

juvenile Phricta. A lichen-coloured specimen with a radically different colour pattern to other juvenile Phricta.
Image: Patrick Honan
Source: Patrick Honan

After reaching adulthood, Phricta can be found higher in the canopy, feeding on the young leaves of trees and shrubs. On particularly windy or stormy nights, they will move down into the lower canopy or into tree holes to shelter from the weather.

ovipositor of Phricta The long, sword-like ovipositor is visible at the end of this juvenile female's abdomen. Her oval-shaped 'ear' can also be seen just below the 'knee' of her right foreleg.
Image: Patrick Honan
Source: Patrick Honan

Like most katydid species, male Phricta call loudly to attract females in the rainforest at night, a sound familiar to people who frequent these forests. Females possess an auditory tympanum (or ear) on their forelegs to pick up the call.

Parasites on the thorax of juvenile Phricta. Parasites on the thorax of juvenile Phricta.
Image: Patrick Honan
Source: Patrick Honan
 

Phricta are attacked by owls and other predatory birds, as well as honeyeaters and brush turkeys. They are also host to parasitic mites, which gather sometimes in large numbers on the top of the thorax. The effects of these mites on the insects are not known.

Phricta can be seen in the 'Diversity' display in Bugs Alive! at Melbourne Museum. Despite being very common and widespread in North Queensland rainforests, this species was not described scientifically until 2005, an indication of how much is still to be discovered and catalogued by science.

Further reading:

Rentz, D., 1996, Grasshopper Country: the Abundant Orthopteroid Insects of Australia, University of New South Wales Press, Sydney, 284pp.

Rentz, D., 2010, A Guide to the Katydids of Australia, CSIRO Publishing, Collingwood, 214pp

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