An aphid is an insect that has mouthparts to sip plant sap. when placed on a herbaceous stem, it soon has its mouthparts embedded and is withdrawing plant sap. sometimes so much plant sap is taken that it cannot use all of it and the aphid secretes droplets of the sugar to attract ants that in turn protect and care for the aphids. what layer of cells has the aphid's mouthparts tapped?