Three sets of melon fly (Zeugodacus cucurbitae) pupae illustrate the changes resulting from CRISPR/Cas9 genetic editing. In the top row, wild-type, unaltered melon fly pupae display a range of normal brown pupae coloration. In the middle row are white pupae mutants obtained in the first generation after using CRISPR to knock out an important gene related to the normal pigmentation in pupal stage of fruit flies. These individuals are called “mosaics,” because only some of their cells harbor loss-of-function mutation in the targeted gene. In the bottom row are white pupae mutants of the melon fly developed after breeding mosaic flies from the first generation. (Photo by Daniel Paulo, Ph.D.)