Localization of the structural precursors of sheath material in the salivary glands of Nephotettix cincticeps UHLER and Laodelphax striatellus FALLEN was investigated. In N. cincticeps, the sheath material originates as two distinct secretions, protein and probable mucolipid, produced respectively in the IV- and V- cells in the principal gland. In L. striatellus, the precursors, protein and unsaturated lipid, elaborated in the A- and coupled G- and H-follicles of the principal gland respectively. In addition, a certain mucosubstance in the accessory gland may enter into the sheath material.