I've been thinking about my bloody colours post of a little while back. Magenta and solferno were named because they reminded observers of the after effects of a battle. What about colours made from actual blood? That is, by killing a critter. These dyes exist, and some are still in use today.
Fantastic reds can be made from crushed insects. I wonder who was the first who thought of grinding up dried bugs to dye cloth? One of these dyes is Kermes, an ancient dye extracted from an insect (Coccus ilicis) that resided in the middle east. This bug lives as a parasite on oaks, producing carminic acid (the base component for a dye) to deter predators. Kermes is the root of the word crimson and predictably, cloth dyed with kermes turns out a bluish-red. Skilled dyers could even produce a scarlet cloth. About 70,000 insects are needed to make only one pound of dye – making a very bloody dye.
Cochineal, also known as carmine, is another ancient bloody dye produced from similar insect (Dactylopius coccus). This bug resides on cactus in Mexico and has been the foundation of a red dye for millennium. This dye is chemically the same as kermes except ten times stronger – less of them needed to die to produce the same amount of dye. When the Spanish brought this dye back to Europe in the mid 1500s, it quickly over shadowed kermes because it was a cheaper alternative. Both kermes and cochineal have been widely used to colour foods dating back to the middle ages, and cochineal is still in use now. As a food colourant it's called by many names, including 'natural red 4'.
Throughout the ages other similar insects have been used to make red dyes. Polish cochineal (Porphyrophora polonica), a insect that lives on the roots of herbs in Poland, was once used to make reds as an alternative to kermes. In India, a red dye was made from a secretion left behind by an insect in the same family (Laccifer lacca), I think the bug got to live in this case – but, I don't know for sure. In South East Asia, reds called lac, could be made from a whole family of related insects, which also provided the foundation for shellac (often used as a protective coat for wood).
Tyrian purple held the title of the most prestigious dye in antiquity. In Roman times if you were caught wearing clothing dyed this purple and weren't royalty it was considered a crime, of course affording this colour if you weren't royalty was virtually impossible. The complex technique for making this dye was discovered around 1500BC by the Phoenicians, an ancient Mediterranean seafaring traders. Tyrian purple is made from a pale yellow mucous secretion from some molluscs, commonly known as sea snails. It is possible to 'milk' these snails, in which case, they wouldn't be harmed – however, this is labour intensive so more destructive methods were used. Often the snails would simply be crushed to get their secretion. From one source, the snails were salted and left for three days to extract the liquid. The liquid was boiled for ten days after which fibers would be soaked in the resulting liquid for five hours. Finally, the resulting fabric would have to be exposed to sunlight where it changed colour from deep yellow, through green and blue to finally purple.
To dye a metre of cloth, 12,000 molluscs would be required (ie killed). Since they were making luxury fabrics, often a fabric would be dyed more than once to get the best shade. Different snails gave different shades, to get the best purple cloth would be first dyed in one species of snails then in another. Fortunately for the snails, synthetic dyes have completely replaced the original tyrian purple.
For more info check here, including some nice pictures.