Defence by Smear: Supercooling in the Cornicle Wax of Aphids

THE cornicles of aphids, despite their definition in the Shorter Oxford Dictionary as the source of honey-dew, in fact secrete a lipid substance, and have a defensive function. Busgen¹ seems to have been the first to have proposed their defensive function, but misconceptions as to their role have persisted. Hottes², for example, considered their function to be excretory, and suggested that they released volatile substances derived from the plant sap on which the animals feed. Their defensive function has not been generally recognized; for example, Roth and Eisner³ neglected them in their review of arthropod defensive mechanisms.