Whether or not ants eat aphids depends on the species of ant. Some species of ants have a mutualistic relationship with aphids and provide food and shelter for them. Others may be predators that attack aphids, but not eat them.
The mutualistic relationship between aphids and ants is beneficial for both parties. Ants provide food and shelter to aphids and aphids provide aphids with a sugar-rich substance called honeydew. These two substances attract ants, who then take care of aphids.
Aphids are small plant-sucking insects that consume plant sap and produce honeydew. Honeydew is a sticky, sugar-rich substance that attracts ants.
Honeydew can grow into sooty mold, which stops sunlight from reaching a plant. This mold weakens plants and makes them easier targets for bacteria and viruses.
Some ant species have a trophobiotic organ that holds honeydew for ants. The trophobiotic organ is not found in wild aphids. However, it does help domesticated aphids.
Some ants have a mutualistic relationship with predators such as ladybirds. These predators can help ants control aphids.
Ants have many natural enemies. Among these are ladybirds, lacewings, flies, and other insects. These natural enemies attack aphids and kill them.
Ants also control aphids by using chemicals that act as pheromone trails. These chemicals act as a mild tranquilizer. Ants can also use strong sprays of water to control aphids.
Aphids can be controlled by using pesticides and ladybugs. Ladybugs are the most beneficial predatory insect. Neem oil is also a good insecticide that can be applied to aphids. Neem oil can be purchased at a local gardening center.