Petasida ephippigera

This grasshopper is known as alyurr in the local Kundjeyhmi language and it plays a role in their mythology.[5]

The species is named after Ludwig Leichhardt. He was the second European to record this grasshopper in 1845 in an area that later would become part of the Kakadu National Park. The species was first recorded by John Dring on the third HMS Beagle expedition a couple of years earlier (during which the type specimen was collected) and it was recorded again by the A.C. Gregory expedition of 1855–56. Subsequently, it went unreported until the early 1970s when it was rediscovered as a result of the emerging mining and ranching industries in the remote region.[2][6]

Both adults and nymphs of the Leichhardt's grasshopper feed almost exclusively on Pityrodia shrubs, including P. jamesii, P. lanuginosa, P. puberula, P. pungens, P. spenceri and P. ternifolia.[2][3][4] They often move little during their life; an individual may stay on a single Pityrodia bush.[2] Although Pityrodia clearly is the main food plant, Leichhardt's grasshoppers have also been reported feeding on Dampiera conospermoides and Gardenia.[6]

Adult males typically are up to about 5.3 cm (2.1 in) long and adult females up to about 6 cm (2.4 in) long.[3][7] Adults of both sexes are bright orange-red with significant blue patches on the head and thorax, and black or very dark blue dappled spots on the abdomen and wings. There are minor local variations; those from Keep River National Park tend to be somewhat paler than those found further east. The nymphs are about 1 cm (0.4 in) long when hatching and the first couple of instars are cryptically coloured in pale green and black; the later instars have an adult-like appearance, but with whitish spots and no or only small emerging wings. The bright colours are aposematic, a warning to potential predators that it is noxious or toxic. While this appears to be highly effective against predatory vertebrates, the effect against predatory invertebrates is limited.[2][3][6]