Polish cochineal, also known as Polish carmine scales, is a scale insect formerly used to produce a crimson dye of the same name, colloquially known as "Saint John's blood". The larvae of P. polonica are sessile parasites living on the roots of various herbs – especially those of the perennial knawel – growing on the sandy soils of Central Europe and other parts of Eurasia. Before the development of aniline, alizarin, and other synthetic dyes, the insect was of great economic importance, although its use was in decline after the introduction of Mexican cochineal to Europe in the 16th century. Historically earlier was used Armenian cochineal scale insect, Porphyrophora hamelii, which is in a same taxonomic family Porphyrophora of the Polish cochineal and in different taxonomic family from cochineal found in the Americas.

The Margarodidae or ground pearls are a family of scale insects within the superfamily Coccoidea. Members of the family include the Polish cochineal and Armenian cochineal and the original ground pearl genus, Margarodes. Beginning in 1880, a number of distinct subfamilies were recognized, with the giant coccids being the first. Although Maskell proposed a new family, many continued to regard the monophlebids as a mere subfamily for many years, and the Margarodidae classification continued to be polyphyletic through the 20th Century. Since then, taking the advice of Koteja several subfamilies and tribes have been elevated into their own families such as Matsucoccidae and Xylococcidae. The pared-down family of Margarodidae is monophyletic.