"Dyers who were disappointed with brazilwood, archil, and lac turned to another set of red dyestuffs, which produced the most vivid and lasting colors of all: oak-kermes, St John's blood, and Armenian red. All three were derived from parasitic insects related to lac, and all of them worked best on animal fibers such as wool and silk, rather than on plant fibers like cotton and linen.
"Oak-kermes had been a valuable source of dye since ancient times. In the days of the Roman Empire, Spain was a key supplier, paying half its substantial tribute in the dyestuff. Found in hot, dry regions along the Mediterranean shore and in the Middle East, oak-kermes lived on the leaves and branches of Mediterranean oak trees and was usually collected in the spring. Although there were several species of the insect, the variety that produced the best color, and was consequently the most valued, was Kermes vermilio. Killed with vinegar and steam, the insects were dried, crushed, packed for market, and sold to discriminating buyers throughout the Mediterranean world and beyond."
Amy Butler Greenfield, A Perfect Red: Empire, Espionage, and the Quest for the Color of Desire (New York: Harper Collins, 2005), 29-30.
"... In the twentieth century, when it finally became possible to analyze the structure of the kermes and cochineal dyes at the molecular level, scientists would reach similar conclusions. To this day the exact composition of these highly complex dyes is disputed, but chemists agree that their primary dyeing agents are closely related. The color of oak-kermes, for example, is produced by kermesic and flavo-kermesic acids, both of which have a chemical structure similar to that of cochineal's chief ingredient, carminic acid; trace amounts of kermesic acid are found in cochineal dye, too. St. John's blood, which contains a mixture of kermesic and carminic acids, is an even closer match for cochineal. The closest match of all is Armenian red, whose chemical composition is almost identical with that of cochineal dye." (page 75)