Most ant species do not feed on plants, but by wandering all over the plant they discourage the presence of other insects, some of which are herbivores at some stage in their lives. Bull-horn acacias provide homes for ants in their thorns. Some plants provide extrafloral nectaries to attract ants. Hosting colonies of these sap-sucking insects might be regarded as a tradeoff that some plants make to enlist the protection of ants. Because their colonies are so large, leaf cutter ants, which do feed on plants, can influence the local distribution of plants.
Harvester ants assist in the distribution of plant seeds.
All insects, whether or not they feed on plants, are important to plants because they transport, concentrate and recycle precious nutrients such as carbon, nitrogen, and trace minerals. Carnivorous plants, like sundews and pitcher plants, supplement their diets with trapped insects. Insects attract other creatures, compounding this nutrient enrichment. Recently, scientists found that even some grasshopper species give something back. One of the protein components in their saliva increases the efficiency of auxin, the plant growth hormone, allowing grazed plants to grow faster.