A demand for organic and environmentally friendly products has inspired some entrepreneurs to concentrate on the production of what is often termed wild silk or tussah. In the production of these materials, the silkworms are allowed to live a more natural existence, feeding on all different kinds of trees and carrying out their entire life cycle. The fibers they produce fluctuate in color due to their varied diet, but are often brownish and may be difficult to bleach. Wild silk is also typically coarser than other silks because it is spun into yarns composed of many broken strands, rather than a seamless single one.