"shield louse," c.1600 of the insect preparation used as a dye, etc.; 1590s of the species of oak on which the insects live, from Medieval Latin cremesinus (also source of French kermès, Italian chermes, Spanish carmes), from Arabic qirmiz "kermes," from Sanskrit krmi-ja a compound meaning "(red dye) produced by a worm."
The Sanskrit compound is krmih "worm" (cognate with Lithuanian kirmis, Old Irish cruim, Albanian krimp "worm") + -ja- "produced" (from PIE *gene-; see genus). The insect lives in the Levant and southern Europe on a species of oak (kermes oak). They were esteemed from ancient times as a source of red and scarlet dye. The dye is harvested from pregnant females, which in that state resemble small roundish grains about the size of peas and cling immobile to the tree on which they live.
From this fact kermes dye was, for a long time, mistaken in Europe as being from a seed or excrescence of the tree, and the word for it in Greek was kokkos, literally "a grain, seed" (see cocco-). This was passed to Latin as coccum, coccus "berry [sic] yielding scarlet dye," in late use "scarlet color, scarlet garment." So important was kermes (coccus) as a commercial source of scarlet dye that derivatives of the name for it have displaced the original word for "red" in many languages, e.g. Welsh coch (from Latin), Modern Greek kokkinos. Cf. also crimson (n.). Kermes dyes have been found in burial wrappings in Anglo-Scandinavian York, but the use of kermes dyes seems to have been lost in Europe from the Dark Ages until early 15c. It fell out of use again with the introduction of cochineal (which might itself be from coccus) from the New World.
Cloths dyed with kermes are of a deep red colour; and though much inferior in brilliancy to the scarlet cloths dyed with real Mexican cochineal, they retain the colour better and are less liable to stain. The tapestries of Brussels and other parts of Flanders, which have scarcely lost any thing of their original brilliancy, even after a lapse of 200 years, were all dyed with kermes. [W.T. Brande, "Dictionary of Science, Literature, & Art," London, 1842]