least some aphid species have evolved in response to their domestic existence. They have lost some of the normal aphid defensive responses and, according to one intriguing suggestion, some have modified their rear end to resemble the face of an ant. Ants are in the habit of passing liquid food to one another, mouth to mouth, and the suggestion is that individual aphids that evolved this rear-end face-mimicry facilitated being ‘milked’ and therefore gained protection by ants from predators.
