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In this short review, we introduce various aspects of insect body lipids, which have been progressively found to have many crucial physiological roles. The body-surface of insects is covered with cuticular lipids, mainly hydrocarbons. The cuticular hydrocarbons are synthesized in specialized cells called oenocytes residing beneath the epidermis. The hydrocarbons synthesized are transported to the outermost layer, wax layer, by the circulating lipoprotein, lipophorin. Although the principal role of the wax layer is the protection of internal body from desiccation, the essential features vary depending on insect species and development stage. The diapausing pupae of large and small cabbage white butterflies change the thickness and unsaturation of their cuticular hydrocarbons from their non-diapausing ones. The cuticular hydrocarbons also contribute to chemical communications. The unsaturated hydrocarbons of male crickets play an important role for sex discrimination before copulation. Modern in-situ surface analytical methods have a potential to provide more abundant and precise information about the structure and physicochemical properties of the cuticular hydrocarbons. Recent ATR FTIR spectroscopic studies indicated the necessity of correction in the phase-separation model of cuticular hydrocarbons proposed by A. G. Gibbs. [ABSTRACT FROM AUTHOR]