It has thin roots, usually only a single stem, between three and six fleshy, cylindrical leaves and up to twenty small, white to cream-coloured flowers.

Octarrhena pusilla is an epiphytic or lithophytic herb usually with a single stem with thin roots.

[2][3] The wispy grub orchid was first formally described in 1889 by Frederick Manson Bailey who gave it the name Oberonia pusilla and published the description in Report of the government scientific expedition to Bellenden-Ker Range: upon the flora and fauna of that part of the Colony.

[6] The specific epithet (pusilla) is a Latin word meaning "very small", "little" or "petty".

[7] The wispy grub orchid grows on mossy trees and rocks in rainforest between the Cedar Bay and Paluma Range National Parks in Queensland.