Ants, belonging to the order Hymenoptera alongside wasps and bees, are one of the most widespread and ecologically successful groups of insects on Earth. Their eusocial structure, where colonies function as a unified superorganism, has allowed them to colonize nearly every terrestrial environment. Scientists estimate the global ant population to be around 20 quadrillion individuals. Their combined biomass of roughly 12 megatons of dry carbon exceeds the total biomass of all wild birds and mammals combined, underscoring their profound influence on global ecosystems.
Global Reach and Climate Influence
Ants have established a presence on every continent except Antarctica, demonstrating remarkable adaptability to diverse global conditions. Temperature and moisture are the primary determinants of ant population density and the number of species present. As ectotherms, ants are highly sensitive to environmental warmth, which directly affects their metabolism and activity levels.
The highest concentrations of ant species and population abundance are found in the tropical and subtropical regions. Moist tropical forests can harbor up to six times the number of ants compared to less suitable habitats. Moving away from the equator toward temperate and polar regions, the number of species and individual ants decreases significantly. However, even in arid regions, the density of actively foraging ground ants can still be high.
Ant Habitats in the Natural World
Ants exhibit a wide range of nesting strategies, allowing them to thrive in virtually all natural terrestrial habitats, from the forest floor to the highest canopies. Many species are subterranean, constructing complex, multi-chambered nests within the soil or under protective cover like rocks, logs, or leaf litter. These underground homes provide stable humidity and temperature, shielding the colony from surface weather extremes.
Other species are strictly arboreal, making their homes high above the ground in trees and specialized plant structures. Arboreal ants may nest in hollowed-out branches, under bark, or by building carton nests from chewed plant fiber. Specialized relationships also exist, such as with plants that provide small cavities, called domatia, or produce extrafloral nectaries to feed their protective tenants.
Ants have also adapted to specialized ecosystems like grasslands and deserts. Grassland ants frequently construct conspicuous soil mounds that optimize solar gain for colony warmth and provide protection from flooding. In high-altitude or arid environments, ants often exploit the “superficial underground compartment,” a network of air-filled voids and fissures between rocks that offers a consistent microclimate despite surface temperature fluctuations.
Ants in Human Environments
Ants have successfully integrated into human-modified landscapes, often becoming synanthropic species that benefit from proximity to human settlements. In urban environments, ants exploit infrastructure for stable nesting sites, establishing colonies under sidewalks, driveways, and within foundations. These locations offer thermal stability and protection from predators and environmental changes.
Agricultural settings, such as fields and orchards, also provide abundant foraging and nesting opportunities. Inside human homes and buildings, ants are drawn by reliable access to food and water. They exploit small structural gaps to gain entry, using wall voids, insulation, and spaces beneath appliances as protected travel corridors and nesting areas.
Once inside, ants often establish satellite nests near sources of moisture, such as bathrooms, or reliable food supplies, like pantries and food preparation areas. Their presence is a direct result of their ability to locate and exploit predictable, concentrated resources within human dwellings.