Sigaus childi is morphologically cryptic and polymorphic in colour, ranging from pale grey through earthy tones to green and black.
Some individuals closely match foliose lichens that grow in rocks in the area, but others more closely resemble gravels or pebbles.
They rely on camouflage rather than hopping to evade predators, and their hops are short: 30–40 cm and 15 cm high.

The wings on S. childi are very small – between 1–2 millimetres (0.039–0.079 in); like most New Zealand grasshoppers, this species is flightless.
Males are 11–13 millimetres (0.43–0.51 in) long; females are twice as large, 21–25 millimetres (0.83–0.98 in).
They have no ears, and do not sing.
Sigaus childi is morphologically cryptic and polymorphic in colour, ranging from pale grey through earthy tones to green and black. Some individuals closely match foliose lichens that grow in rocks in the area, but others more closely resemble gravels or pebbles. They rely on camouflage rather than hopping to evade predators, and their hops are short: 30–40 cm and 15 cm high.
The wings on S. childi are very small – between 1–2 millimetres (0.039–0.079 in); like most New Zealand grasshoppers, this species is flightless. Males are 11–13 millimetres (0.43–0.51 in) long; females are twice as large, 21–25 millimetres (0.83–0.98 in). They have no ears, and do not sing.
Sigaus childi