Although the silkworm Bombyx mori is an insect of great economic importance, it has until now resisted efforts for efficient germline transgenesis, most likely because the usual insect transgenesis strategies rely on transposons that do not function in lepidopteran insects like silkworms. Toshiki et al. now have succeded in silkworm transgenesis using piggyBac, a transposon discovered in another lepidopteran species. In this study, they transformed the silkworms with GFP and got glowing green worms. One can easily imagine more pragmatic applications, however, like engineering silk glands for production of novel fibers or proteins of pharmaceutical interest (see p. 81).