Ants will protect certain sap-feeding insects, such as treehoppers and aphids, from predators in exchange for a sugary substance that they produce called honeydew. In this image, an ant is guarding a group of aphids. When I approached the ant to take this photograph, it stood guard over the aphids briefly while determining if I was a threat. When it realized that I wasn't, it continued to climb over the aphids, gently touching them with its antennae, to try to encourage them to release honeydew.