Ants are found in all parts of the world where the soil is not permanently frozen. Their feeding habits range from eating anything they find (omnivory) to eating only plants (herbivory), animals (carnivory), or fungi (fungivory). A given species of herbivore may specialize on seeds (granivory), nectar or sap (nectivory), fruit (frugivory) or other plant parts. Carnivorous ants are more general in their diet, but the tiny grease ants that invade kitchens prefer fats while others eat primarily meat. No ants are known to feed on blood like ticks and mosquitoes do. Most fungivorous ants feed on a single species or a few closely related species of fungi that they grow in their underground chambers. They often become household and garden pests.
- Granivorous Ants
Harvesting ants are found throughout the world. Stephen Welton Taber found they carry seeds to their nests and store them in chambers designed to keep the seeds from germinating. If seeds show signs of germinating, they may be carried back to the surface for further drying. Workers with specialized jaws are able to crack the seeds for distribution to the other ants in the colony. They are not totally dependent on seeds, and consume other plant and animal foods they may find in their travels. More information about these fascinating insects can be found in Taber's "The World of the Harvester Ants."
- Nectivorous Ants
- Sap Drinking Ants
These ants do not obtain sap directly from plants. Rather, they tend large numbers of sap sucking insects called aphids. Aphids that are tended by ants are often called “ant cows.” The ants that tend them are called “aphid farmers.”
Aphids puncture the stems, buds, leaves, and flowers of plants; insert their pointed beaks into single food transporting cells, phloem cells, of the plant; and sip the sap. The sap in the phloem cell is pressurized and forces the sap through the aphid faster than the aphid can extract all its nutrients. The sap is excreted from the intestine as sweet honeydew that dries to a sticky, sugary liquid that may cover the plant and fall to the ground or automobiles parked beneath trees.
The aphid farmer ants approach aphids from the rear and stroke the aphids' backsides with their antennae, much as they would stroke a nest mate. Each aphid releases a drop of honeydew for the ant. The ants, in turn, protect the aphids from predators and transport them to new plants to feed on. Thus, the relationship is mutualistic: benefiting both ants and aphids.
- Honey Pot Ants
Desert and tropical honey aphid farming ants bring the honeydew back to the nest where they transfer it to a specialized caste: the honey pots or repletes. Honey pot ants spend their lives hanging from the ceilings of the nest chambers and may swell to the size of a small grape from all the nectar they are fed. While storing the nectar, the honey pot ant removes much of the water from the nectar, concentrating it and turning it into an enriched honey-like substance. When a hungry worker uses its antennae to stroke the face of the honey pot ant, the honey pot then regurgitates a drop of its honey into the mouth of the worker.
Honey ants vigorously protect their honey pots. They have a soldier caste with huge jaws that prevent nest robbing ants and other insects from getting into the honey pot chambers.
- Carpenter Ants
Unlike termites, ants do not eat and digest wood. They do tunnel into trees, old logs, and wooden human buildings to build their nests. These nests can be huge; sometimes twenty or thirty cubic feet of a tree or building will be riddled. The ants are omnivorous, eating a wide variety of plant and animal matter.
- Carnivorous Ants
Very few ants eat only meat, but the tropical army ants of America and Africa are an exception. Rather than foraging in a thin line like most ants, army ants rapidly move along a broad front, eating every helpless and slow-moving animal in their path, but leaving the vegetation untouched.
Army ants do not make underground nests where the queen and brood are tended. Instead, they bring the queen and larvae with them as they travel through the forest. They establish “territories” called bivouacs, where the brood is tended. They move the queen and young only when the foraging ants find it difficult to return to their bivouac each evening.
- Fungivorous Ants
Parasol ants of many continents climb high into trees, cut dime-sized semi-circles from leaves, and carry them to their nests for storage. Instead of eating the leaves, the ants place the leaves into subterranean fungus-growing beds and eat the fungi that grow on the leaves. Most species of parasol ants feed on a single species of fungus, removing and destroying any foreign fungi that invade their chambers. The symbiosis between the ants and the fungi is sometimes so strict that the fungus might not live anyplace else but in the ant colonies and the ants starve to death if the fungus does not grow. This makes the ant-fungus symbiosis one of the strictest mutualistic relationships in the world.
Ants eat a wide variety of foods, and almost everything organic is utilized by one species or another. The life histories of ants are also interesting.
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