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Worms produce pre-colored silk after eating dyed leaves


December 5, 2013

Silkworms chowing down on one of their favorite foods – mulberry leaves 
(Photo: Shutterstock)

Silkworms chowing down on one of their favorite foods – mulberry leaves (Photo: Shutterstock)

Image Gallery (2 images)

Like most other fabrics, silk is colored with dye. Unfortunately, the dyeing process results in wastewater laden with toxins. Now, however, scientists from the National Chemical Laboratory in India are developing an alternative. They're feeding dye to silkworms, which in turn are producing pre-colored silk fibers.

The researchers sprayed or dipped mulberry leaves in seven types of azo dye, which is the dye family most commonly used in the food and textiles industries. Those leaves were then fed to Bombyx mori silkworms.

Of the seven dyes, it was found that three ended up making their way into the worms' silk, causing it to take on the color of the dye. None of the dyes appeared to affect the worms' health.

Silkworms that consumed Direct Acid Fast Red azo dye produced these red fibers

This isn't the first time that silkworms have produced colored silk after eating dye, although the type of dye used in previous efforts was reportedly too expensive for commercial use. Azo dyes, by contrast, are relatively cheap.

A paper on the research was recently published in the journal ACS Sustainable Chemistry & Engineering.

Source: American Chemical Society

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

If "the type of dye used in previous efforts was reportedly too expensive for commercial use", somebody was not looking previous enough. I have a century-old sample of the fact that the same silkworms that produce white silk when fed on mulberry leaves produce beautiful golden thread from oak leaves -- easier to obtain than mulberry, which is why my mother used them.

The problem both new and old is control: if you want a particular gold (or green, or mauve, or ...), not just a colour in a particular ball-park, it will take a lot more experiment to get it than you need with a dye-vat.


Okay - so perhaps a stupid question, but I have seen dyed flowers - so could you do the same with cotton - I am going to guess not without reverting to some clever gene splicing


I wonder about scalability. It is one thing to dip leaves in dye, quite another to dip a tree or bush.

Bruce H. Anderson

@Bruce H

You could probably inject it into the trunk, so it was taken up by the tree's water distribution system into the leaves.

For their next project they're working on a way to make cows give chocolate milk. :-)


Just checked Wikipedia and found problematic issues. These are excerpts from the article:

Many azo pigments are non-toxic, although some, such as dinitroaniline orange, ortho-nitroaniline orange, or pigment orange 1, 2, and 5 have been found to be mutagenic.[3] Likewise, several case studies have linked azo pigments with basal cell carcinoma.[4]

Azo dyes derived from benzidine are carcinogens; exposure to them has classically been associated with bladder cancer.[7] Accordingly, the production of benzidine azo dyes was discontinued in the 1980s "in the most important western industrialized countries".[8]

some aliphatic azo compounds are utilized as radical initiators. Because of their instability, aliphatic azo compounds pose the risk of explosion.

Certain azo dyes can break down under reductive conditions to release any of a group of defined aromatic amines. Consumer goods which contain listed aromatic amines originating from azo dyes were prohibited from manufacture and sale in European Union countries in September 2003.

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