Discover: Researchers have genetically modified silkworms to produce a hybrid silk that’s partly from silkworm and partly from spider. Spider silk is extraordinarily strong and tough and can stretch several times its original length. Farming spiders has not proven as practical as farming silkworms, however, because spiders are territorial and cannibalistic. So Donald Jarvis and Randy Lewis of the University of Wyoming and Malcolm Fraser of the University of Notre Dame inserted spider silk genes into the silk-making glands of silkworms. Although the new silk is only 2–5% spider silk, it is stronger, more elastic, and twice as tough as normal silkworm fiber. Spider silk could have many uses, such as in sutures, artificial ligaments, and body armor.