Since 1996 plants have been modified with short sequences of genes from Bt to express the crystal protein Bt makes. With this method, plants themselves can produce the proteins and protect themselves from insects without any external Bt and/or synthetic pesticide sprays. In 1999, 29 million acres of Bt corn, potato and cotton were grown globally. It has been estimated that by using Bt protected cotton, the United States was able to save approximately $92 million.Bt GM crops are protected specifically...