For some 5,000 years, cultivated silkworms have been spinning luxurious white silk fibers destined for use in the finest clothing. But current dyeing practices produce wastewater that contains potentially harmful toxins, so scientists are turning to a new, “greener” dyeing method in which they coax already-colored fibers from the caterpillars by feeding them dyed leaves.

They dipped or sprayed mulberry leaves, the silkworm’s food of choice, with azo dyes to see which ones, when consumed, would transfer to the silk. Of the seven dyes they tested, three were incorporated into the caterpillars’ silk, and none seemed to affect the worms’ growth.

This isn’t even the first time in the last year that silkworms have been the subject of experimentation. Back in July of 2013, Japanese scientists genetically engineered silkworms to create fluorescently reactive red, green and orange silk.

Via Phys.org.