April 6, 2015

Bugs to Dye for: The Colorful Science and History of Cochineal

by Christine Hoekenga

What gives that red hue to your strawberry yogurt or the pinkish tint to the vitamin tablet you take every morning? It just might come from an insect.

For hundreds of years, a small, parasitic bug in the superfamily Coccoidea (or “scale insects”) has been used to produce a crimson dye. These insects, known as cochineal, feed on prickly pear cactus, which are common in Central America, Mexico and the southwestern U.S. Adult female cochineal bugs are legless and wingless. They use their mouth parts to pierce the cactus’ fleshy pads and extract water and nutrients.

Femail cochineal bugs

A cluster of female cochineal bugs on a prickly pear cactus.

Once attached to a pad, a cochineal bug stays put for the rest of its life cycle. For protection, the bug produces a tuft of white material resembling cotton that acts as camouflage and traps moisture. The insect also produces and stores carminic acid, a bright red substance that tastes awful to predators but makes cochineal very interesting to enterprising humans.

chemical structure of carminic acid

The chemical structure of carminic acid.

During the 15th century, when Spanish explorers came to the Americas, they discovered that the local people dried and ground up cochineal and used the powder to make beautiful textile dyes. Depending on the processing, cochineal can produce brilliant reds, purples and oranges. It is also colorfast, meaning that it resist fading and does not rinse out of  fibers when they are washed.

Cochineal quickly became a major export to Spain and other parts of Europe, where it was used to dye textiles for royally and members of the clergy. The exact source of the dye was kept secret for many years, and initially many believed it came from the cactus itself. Attempts to establish cochineal farms elsewhere in the world were mostly unsuccessful but led to the spread of prickly pear cactus to many other regions. In some cases, the cactus escaped from cultivation and became an invasive pest.

Indian Collecting Cochineal with a Deer Tail by José Antonio de Alzate y Ramírez (1777)

In the late 1800s, cheaper synthetic dyes became available, and cochineal lost favor in the textile industry. It is still used to dye wood and fiber used in folk art and has recently seen a resurgence as a natural coloring agent in food, pharmaceuticals and cosmetics such as lipstick. In the U.S., cochineal received FDA approval as a food and cosmetic additive in 1969. On labels it may be listed at “cochineal extract” or “carmine.”

So next time you pick up a food or beverage with red or pink coloring, scan the label. You just might be eating the same ingredient used to dye the cloaks of Roman Catholic cardinals and the “redcoats” worn by British soldiers.

Learn more about prickly pear cactus and cochineal from the Arizona-Sonora Desert Museum.

See more pictures and learn about other uses of cochineal from the Houston Museum of Natural Science.

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Written by

Christine is a freelance writer, editor, and content strategist, specializing in science and nature. She holds an Bachelor's degree in Environmental Science and Media Studies and a Master's of Science Writing. She has been working in science communication and education for nearly a decade as a journalist, an organizer for conservation groups, and a museum educator. Before joining the Visionlearning team, she served as the New Media and Online Community Manager for the Webby award-winning Smithsonian Ocean Portal. Christine is assisting Visionlearning with developing new modules and glossary terms, managing the blog, and outreach through social media.

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