This small passerine bird is found in short dense vegetation, often close to water. It is a medium-sized warbler about 13 cm long. The adult has a streaked brown back and whitish grey underparts which are unstreaked except on the undertail coverts. The sexes are identical, as with most warblers, but young birds are yellower below.

 Its diet includes flies, moths, beetles, aphids, dragonflies and mayflies and their larvae. Spiders and woodlice are also eaten.

The song is an unmusical long, high-pitched reeling trill performed with beak held wide open and the whole body vibrating. It lasts for from a few seconds to two or three minutes with hardly a pause for breath.