Cochineal, the red that came from a bug

Some of the most prized reds in European textiles and painting came from an insect. Dactylopius coccus is a small scale insect that feeds on prickly pear cactus. The females make carminic acid, a deep red compound, and when they are dried and crushed that colour can be turned into dye. It takes roughly 70,000 dried insects to make about 450 grams of dye.¹ In Nahuatl, the language of the Aztecs, the dye was called nocheztli, "blood of the prickly pear".¹

Before the Spanish

Cochineal was farmed in Mexico long before Europeans arrived. Growers raised the insects on cactus pads, and the finished dye was valuable enough to be demanded as tribute from conquered peoples.¹ The Codex Mendoza, a record of Aztec tribute made for the Spanish in the 16th century, draws it as a bag of red grains. A Spanish note beside the picture reads "grana que llaman cochinilla", the grain they call cochineal.²

A Spanish trade

Hernán Cortés reached Mexico in 1519, and the Spanish soon saw what the dye was worth. Europe's own reds had limits. Madder root was cheap but gave a duller colour, and kermes, made from a different insect, was costly.¹ Cochineal gave what one historian calls the "brightest, strongest red the Old World had ever seen".³ Spain turned it into one of its main colonial commodities and kept close control of how and where it was grown.³ By the start of the 17th century somewhere between 250,000 and 300,000 pounds a year were being shipped to Spain, and in the 18th century the only export from New Spain worth more was silver.¹

Seed, worm or insect

The dye reached European markets as small, hard, dark grains, and for a long time buyers argued about what they were. The Spanish word grana, grain, suggested a seed.² One popular idea held that it was a worm that grew out of a rotting berry.¹ Meanwhile naturalists tried, without permission, to get hold of live insects and cactus plants so they could grow their own outside Mexico.³

The microscope settled the question. Nicolaas Hartsoeker described cochineal as an insect in 1694.¹ Ten years later Antoni van Leeuwenhoek, the Dutch lens maker, sent the Royal Society in London a letter dated 21 March 1704 with drawings of the insect, its eggs and the six-legged young that hatched from them. The Society recorded that the letter proved cochineal to be "an Insect".⁴

Coats and canvases

Cochineal ended up in uniforms. British army officers' coats were dyed with it, giving a deep crimson, while the coats of ordinary soldiers were usually dyed with cheaper madder, which gave a brighter scarlet.⁵ The difference in colour marked rank as well as cost.

Painters used it too, as a lake pigment. A lake is made by fixing a dye onto a fine, colourless powder, often alumina, so that it can be ground into paint. The result is a transparent red that glows when laid over other colours. Artists knew the cochineal versions as carmine or crimson lake. Cochineal and, later, madder were the main dyes used for red lakes in the 18th and 19th centuries, and the recipes changed over that time as pigment makers changed their methods.⁶

Why the bug makes it

The insect does not make carminic acid for anyone's benefit. In 1980 Thomas Eisner and colleagues at Cornell showed that carminic acid is a strong feeding deterrent to ants and suggested it evolved as a chemical defence. They also found a predator that ignores it. The caterpillar of a small moth, Laetilia coccidivora, eats cochineal insects and reuses the acid to protect itself.⁷

Still in use

Synthetic dyes pushed cochineal aside in the 19th century, but it came back as a colouring for food and cosmetics.³ In the EU it appears on labels as E120, which covers cochineal, carminic acid and carmines.⁸ Peru is now the leading producer and supplies most of world demand. The Canary Islands still produce a small amount, around 2,000 to 3,000 kilograms of dry cochineal a year by 2011, down from 14,000 kilograms in 1980.⁹

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1. Mark Cartwright, Cochineal, World History Encyclopedia, 2022.
2. Wired Humanities Projects, nocheztli (Codex Mendoza, folio 43r), Visual Lexicon of Aztec Hieroglyphs, University of Oregon.
3. Publishers Weekly, Review of A Perfect Red: Empire, Espionage, and the Quest for the Color of Desire by Amy Butler Greenfield, Publishers Weekly, 2005.
4. The Royal Society, Observations of the cochineal (scale insect), Royal Society Picture Library.
5. Fashion Archives and Museum, Global trade on one soldier's back, Fashion Archives and Museum, Shippensburg University, 2019.
6. Jo Kirby, Marika Spring and Catherine Higgitt, The technology of eighteenth- and nineteenth-century red lake pigments, National Gallery Technical Bulletin, vol. 28, 2007.
7. T. Eisner, S. Nowicki, M. Goetz and J. Meinwald, Red cochineal dye (carminic acid): its role in nature, Science, vol. 208, 1980.
8. European Food Safety Authority, Scientific opinion on the re-evaluation of cochineal, carminic acid, carmines (E 120) as a food additive, EFSA Journal, 2015.
9. Desiree Martin, Spanish islands launch cochineal comeback, AFP via Taipei Times, 2011.