Black ants (Lasius niger) milking aphids (Aphis sp.) for honeydew. Aphids drink plant sap, which is rich in sugars, and secrete honeydew as they feed. Ants feed on this secretion, drinking it directly or taking it back to their nest to feed their young. They stimulate the aphids with their antennae to prompt them to secrete a new blob. The ants are known to be protective of their livestock, chasing away predators such as ladybirds.