The lipid composition of the larval fat body of P. regina was analysed at different periods during 3rd-instar development. Lipid represented 21.8% of the fat-body dry weight in the early 3rd-instar, whereas in the mature larva it constituted 52.5%. Fractionation of the lipid into triglyceride, partial glycerides (includes free fatty acids), and phospholipid was accomplished using column and thin-layer chroma -tography. Triglyceride was found as the predominant lipid class accounting for almost 90% of the total lipid of the prepupal fat body. Fatty-acid analysis of the 3 lipid fractions, emplcying gas-liquid chroma -tography, revealed the presence of 3 major (palmitoleic, oleic, and palmitic) and 3 minor (myristic, stearic, and myristoleic) fatty acids. The major fatty acids constituted 81.6 to 96.8% of the total fatty acids and in general palmitoleic acid predominated. Phospholipid exhibited a greater percentage of palmitoleic and oleic acids than did triglyceride with the exception of the prepupal fat body. The change in the pattern of distribution of fatty acids in the prepupa resulted from a decline in the percentage of palmitoleic and oleic acids of phospholipid with a corresponding increase in the percentage of palmitic acid. The distribution of fatty acids in triglyceride did not change appreciably during development.
