The adult striated thornbill is 9–10 centimetres (3.5–3.9 in) long and weighs around 7 grams (0.25 oz). It has a russet- or orange-brown crown with cream streaks, dull yellow-olive upperparts, olive-grey flanks, and cream underparts heavily streaked with black.
The brown thornbill (A. pusilla ) is similar but lacks the white-streaked orange-brown cap and lives in shrubs.
The striated thornbill is predominantly insectivorous, generally forages in the canopy of eucalypt trees, gleaning leaves for prey. It often hangs upside-down while foraging. The striated thornbill also visits and feeds on extra-floral nectaries on the leaves of sunshine wattle (Acacia terminalis ), helping pollinate the plant as it brushes against flower heads while feeding.
Striated thornbills form flocks of 7–20 birds outside of breeding season from late summer to winter, before breaking up into groups of 2–4, composed of a breeding pair plus helper birds.
