Ants exhibit incredibly diverse feeding strategies. With over 12,000 described species, their food preferences vary dramatically, ranging from generalist scavengers to highly specialized farmers and nomadic predators. This vast array of dietary niches means that the label applied to one species may be entirely inaccurate for another. The complexity of the ant diet is a reflection of their ability to exploit nearly every terrestrial habitat. Most ants are not strict herbivores.
Classifying Ant Diets
Most ant species are accurately classified as omnivores, consuming both plant and animal matter. While a strict herbivore eats only plants and a carnivore eats only meat, the majority of ants thrive on a mixed diet. This generalist approach provides colonies with the flexibility needed to survive environmental changes and exploit locally abundant resources.
The nutritional needs of an ant colony are split between carbohydrates and proteins. Carbohydrates are the primary energy source for adult worker ants, fueling foraging and nest maintenance. Protein is necessary for the growth and development of the larvae and for the queen’s egg production. Adult foragers seek out energy-rich sugars for themselves, but they must also return to the nest with protein-rich food for the developing young.
Common Food Sources of Generalist Ants
Generalist ant species focus their foraging efforts on finding readily available sources of sugars and protein. For carbohydrates, they seek out natural sweet liquids like flower nectar and sap from damaged plants. These liquids provide the quick energy necessary for the workers to maintain their high level of activity.
A significant source of sugar comes from the symbiotic relationship ants form with sap-sucking insects, such as aphids, scale insects, and mealybugs. These insects excrete a sugary waste product known as “honeydew,” which ants eagerly collect. Worker ants often protect these insects from predators in exchange for this sweet, liquid resource, effectively farming them for carbohydrates.
For their protein requirements, generalist ants are highly efficient scavengers, relying on dead or dying arthropods. They also actively prey on small, soft-bodied insects or the eggs of other invertebrates, which are carried back to the nest. Solid protein material is fed to the larvae, as adult ants are restricted to consuming only liquid foods. The protein is broken down by the larvae and then shared with the adults through a mouth-to-mouth process called trophallaxis.
Highly Specialized Feeding Behaviors
While most ants are omnivorous generalists, some specialized species lean heavily toward a herbivorous or carnivorous lifestyle. The leafcutter ants of the New World tropics are renowned for their agricultural practices. They harvest plant material but do not consume it directly. Instead, they use the cut leaves as a substrate to cultivate a specific fungus within their nests, and the fungal growth is the sole food source for the entire colony.
This makes leafcutter ants technically fungivores, relying on a cultivated food source fed by plant matter. Another group, the harvester ants (granivores), subsist almost entirely on collected seeds and grains, which they store in underground granaries. This seed-collecting behavior is the closest any ant comes to being a true herbivore, though they still require some protein, often sourced from the nutrient-rich elaiosome attached to the seed.
On the opposite end are obligate predators, such as army ants and driver ants, which exemplify a purely carnivorous diet. These nomadic species do not maintain permanent nests. They move in columns, overwhelming other insect colonies and small vertebrates in a “raid.” They rely on this mass-predation strategy to feed their colossal colonies, which can number in the millions. These predatory species often have specialized physical adaptations, such as powerful mandibles, to aid in capturing prey.