In this monograph is written about breeding of mulberry silkworm in areas with extreme environmental conditions and global changes in weather and climatic conditions on the globe, urgently dictate the need for intensive development of new methods of selection and reproduction of plants and animals adapted to the changed environmental conditions. Creation of breeding populations providing normal level of growth, development, reproduction, silk productivity in less favorable conditions reflects the interests of the silk industry in obtaining high cocoon yields in the regions differing significantly in zonal features.The monograph is intended for students, postgraduates, senior researchers and scientific teachers. This monograph was written on the basis of the results of scientific research on "Creation and introduction of mulberry silkworm hybrids for extreme environmental conditions".