A resinous excretion of the insect Laccifer (Tachardia) lacca Kerr, order Homoptera, family Coccidae. Different resiniferous trees of India serve as host trees as the season progresses. The insects suck the juice of the tree and excrete “stick-lac” almost continuously. Whitest shellac is produced while the kusum tree (Schleichera trijuga) is the host. Most shellac is produced in the Central and in the United provinces of India and in the states of Bihar and Orissa. The major component of lac is a resin which upon mild hydrolysis gives a complex mixture of aliphatic and alicyclic hydroxy acids and their polyesters. The composition of the hydrolysate depends on the lac source and the time of collection. The major component of the aliphatic fraction is aleuritic acid, q.v.; the major component of the alicyclic fraction is shellolic acid, q.v.: Yates, Field, Tetrahedron 26, 3135 (1970). Physical and chemical properties of shellac: Cockeran, Levine, J. Soc. Cosmet. Chem. 12, 316 (1961). Trends in shellac chemistry: eidem, Am. Ink Maker 39 (7), 26 (1961); E. Hicks, Shellac, Its Origin and Applications (Chemical Publ. Co., New York, 1961). Review: J. Martin in Kirk-Othmer Encyclopedia of Chemical Technology vol. 20 (Wiley-Interscience, New York, 3rd ed., 1982) pp 737-747.