Aphids are small, plant-sucking insects harmful to many commercially important plants. Although humans consider them pests, aphids are important to a number of species of ants. For example, honeydew ants keep herds of aphids and periodically “milk” them for their honeydew by stroking the aphids gently with their antennae. Ants will aggressively protect their aphids and may even move them when they are in danger, transferring them into temporary shelters or new nests. Some ant species also move their aphids into underground shelters or burrows during the winter months.

Aphids are small insects found throughout temperate regions of the world. They parasitize a variety of wild and commercially important plants by sucking out plant fluids. Because aphids exude a sweet, sticky fluid that can be used by certain species of ants, herds of aphids are often found guarded and tended by ants.