The evolution of ideas on insect metamorphosis -- A spectacular diversity of forms and developmental modes -- The ametabolan development -- The hemimetabolan development -- The holometabolan development -- Hormones involved in the regulation of metamorphosis -- Molecular mechanisms regulating hormone production and action -- Epigenetic-related mechanisms -- Molting : the basis for growing and for changing the form -- Regulation of ametabolan, hemimetabolan, and holometabolan development -- The origin of hemimetaboly -- The evolution of metamorphosis.