Crimson is the colour of two insects, and its history is the history of what people would pay for them.
Kermes comes from Kermes vermilio, a scale insect living on the kermes oak around the Mediterranean. The dried bodies of the females yield a deep red dye, the word crimson descends from the Arabic qirmiz by way of Old Spanish, and the same root gives carmine. Kermes was the prestige red of the ancient and medieval Mediterranean, and the quantity of insects needed for a bolt of cloth put it far beyond ordinary use.
Cochineal comes from Dactylopius coccus, a scale insect farmed on prickly pear cactus in Mesoamerica, and it is far stronger: it yields perhaps ten times the dye of kermes for the same weight. The Spanish encountered organised cochineal production in Mexico, took control of it, and made the dried insects one of the most valuable exports of the American empire after silver. The crown kept the biological origin obscure for as long as it could, and European naturalists argued for over a century about whether the commodity was a seed, a berry or an animal.
The consequence is that the reds of European rank, the cardinal's robe and the soldier's coat among them, were paid for by an insect harvest on another continent. When synthetic alizarin and the aniline reds arrived in the second half of the nineteenth century, the cochineal industry collapsed within a generation, and the colour that had signified rank became available to anyone.