The common grasshopper warbler (Locustella naevia) is a species of Old World warbler in the grass warbler genus Locustella. It breeds across much of temperate Europe and the western Palearctic. It is migratory, wintering in north and west Africa. This is a species which skulks in the undergrowth, creeping through bushes and low foliage, and which is very difficult to see except sometimes when singing from a prominent position. The song, which gives this species its name, is a monotonous mechanical insect-like reeling, often given at dawn or dusk.