The genus Picobia Haller (Acari: Syringophilidae) is revised. The species of this genus are permanent parasites living in quills of bird body feathers. In total 19 species are recognized. Four new species are described from passerine birds (Passeriformes): Picobia locustella sp. n. from Locustella naevia (Sylviidae), P. biarmicus sp. n. from Panurus biarmicus (Panuridae), P. sturni sp. n. from Sturnus vulgaris (Sturnidae) and P. cissa sp. n. from Cissa chinensis (Corvidae). Two species are redescribed: P. dryobatis (Fritsch) and P. zumpti (Lawrence). A neotype for P. dryobatis is designated. A new diagnosis for the genus Picobia and a key to females are provided. Parsimony analysis of the genus is conducted. Host-parasite relationships are briefly discussed.