A list of parasitoids of the genus Coccophagus Westwood that parasitize the soft scale Parasaissetia nigra (Nietner), in the world, is given. Data on the biology of P. nigra in Mexico are presented. A key to species of Coccophagus associated to P. nigra in Mexico, including possible species of parasitoids, was prepared. A new species, Coccophagus minor Myartseva sp. nov., reared from P. nigra on mistletoe, Phoradendron quadrangulare (Kunth) Griseb., growing over leaves and shoots of huisache, Acacia farnesiana (L.) Willd., in Tamaulipas, Mexico, is described.