any of numerous tiny soft-bodied insects of the family Aphididae of worldwide distribution, that suck the sap from the stems and leaves of various plants, some developing wings when overcrowding occurs: an important pest of many fruit trees and vegetable crops.
1884, Anglicized from Mod.L. aphides, pl. of aphis, coined by Linnaeus (1758), though where he got it and why he applied it to the plant louse are mysteries. The theory favored by OED as "least improbable" is that it derives from the pl. of Gk. apheides "unsparing, lavishly bestowed," in ref. either to the "prodigious rate of production" of the insects or their voracity. They also are known as ant-cows.