Great medieval scientist-polymath Abu Rayhan Al-Beruni (973–1050) wrote in his book “Pharmacognosy” about some kind of “worms” inhabiting willows in Azerbaijan and Southern Iran and used by native people for producing of a red dye. It was unclear during one thousand years which organisms Al-Beruni noted as those dye-producing “worms”. Some modern authors even suggested that the relevant medieval text was partly erroneous. To the contrary, in the present paper we, for the first time, consider some species of the felt scale insects (Coccinea: Eriococcidae) as the organisms, which have probably been used for the production of the red dye in the medieval countries of Western and Central Asia. These insects are several species from two closely related genera Acanthococcus Signoret, 1875 and Gossyparia Signoret, 1875. The review of biological characters, identification key, new figures and colour photographs are provided for the species of Acanthococcus and Gossyparia associated with Salix spp. in the Asiatic Region. Acanthococcus turanicus Matesova, 1967, syn. nov. is placed in synonymy with A. salicis (Borchsenius, 1938), and A. altaicus Matesova, 1967, syn. nov. is placed in synonymy with A. spiraeae Borchsenius, 1949. Earlier discovered synonymy of A. melnikensis (Hodgson et Trencheva, 2008) with A. aceris Signoret, 1875 is discussed. Some other dye-producing scale insects and their pigments are also briefly considered.
