Ants and aphids share a relationship of mutualism. Ants feed on the sugary honeydew left behind by aphids. In exchange, the ants protect the aphids from predators and parasites. Aphids suck the sugar-rich fluids from their host plants. Because these liquids are low in nitrogen, the aphids must consume large quantities of them to gain adequate nutrition. The aphids then excrete equally large quantities of waste, called honeydew, which is high in sugar content.