Ants that build mounds are well-known for creating impressive and complex structures above the ground. These mounds serve as protective homes for the colony, housing thousands of individuals in a highly organized system of tunnels and chambers. The size of the mound can vary from a few inches to several feet, depending on the species and the age of the colony. They are often constructed from soil, sand, leaves, and other organic materials carefully packed together.
The design of a mound is not random—it is highly functional. Chambers inside the mound are used for nurseries, food storage, and resting areas, while tunnels allow safe movement throughout the colony. The external structure also provides ventilation, helping regulate temperature and humidity inside the nest. Some mounds even have specialized openings that prevent flooding during heavy rains.
Building a mound is a cooperative effort that requires teamwork. Worker ants continuously gather soil and organic matter, carrying it back to the nest to expand or repair the structure. Over time, these collective efforts create a mound that can dominate the surrounding landscape, sometimes standing out as a visible landmark in forests, fields, or gardens.
Location plays a critical role in mound construction. Colonies often choose sunny areas to maintain warmth or solid ground to ensure stability. Proximity to food sources is also important, allowing for efficient foraging trips. Some mound-building ants even orient their nests in a way that optimizes internal climate conditions, showcasing remarkable environmental adaptation.
Ants that Build Mounds
Red Imported Fire Ant (Solenopsis invicta)
These notorious ants build distinctive, dome-shaped mounds in open, sunny areas like lawns and pastures. The mounds have no visible entry holes and are made of fine, loose soil. When disturbed, the ants swarm out aggressively to defend the nest, delivering painful stings. Their mounds can be over 18 inches high and house hundreds of thousands of workers.
Allegheny Mound Ant (Formica exsectoides)
Found in the eastern United States, these ants construct large, conical mounds that can reach several feet in height and diameter. They clear all vegetation from around their mound and use formic acid to kill competing plants, creating a striking, barren circle. Their mounds, built from soil and organic debris, can last for decades.
Red Wood Ant (Formica rufa group)
Common in European and North American forests, these ants build massive, domed mounds primarily out of organic materials like pine needles, twigs, and resin. These thatched mounds can be over 6 feet tall and house millions of ants. The organic material helps regulate the nest’s internal temperature and humidity.
Yellow Meadow Ant (Lasius flavus)
This European species builds low, grassy mounds in meadows and pastures. The ants farm root aphids underground, and the mound is a byproduct of their tunneling, created from the excavated soil. Over many years, these mounds can become large, stable features of the grassland ecosystem, often colonized by specific plants.
Texas Leafcutter Ant (Atta texana)
These ants construct massive, subterranean nests marked by large, irregular craters of excavated soil at the entrance. The mounds themselves can be over 20 feet in diameter, with the complex underground fungus gardens and chambers extending over 15 feet deep. The excavated soil is finely granulated and forms a conspicuous, unstructured hill.
Harvester Ants (Pogonomyrmex spp.)
Known for collecting seeds, Harvester Ants build characteristic mounds in arid and semi-arid regions. They typically clear a wide, circular area around the nest and create a crater-shaped mound with a single, central entrance. The mound is made of fine gravel and soil, and the cleared area helps protect them from predators.
Thatching Ant (Formica obscuripes)
Common in western North America, these ants build large, conspicuous mounds from a thatch of plant materials like grass, stems, and pine needles. The thatch acts as a solar collector, warming the nest during the day and providing insulation at night. These mounds can be several feet high and are fiercely defended by the colony.
Green-Tree Ant (Oecophylla smaragdina)
While they don’t build soil mounds, these Asian and Australian weaver ants construct magnificent nest “mounds” in trees by weaving leaves together. Using silk produced by their larvae, they pull leaves into large, waterproof, globe-like structures high in the canopy. These living nests can be several feet across and house extensive colonies.
Southern Wood Ant (Formica rufa)
A close relative of the Red Wood Ant, this species also builds large, thatched mounds in woodland areas. Their mounds are engineering marvels that maintain a stable internal climate for raising brood and cultivating the symbiotic relationships they have with aphids they “milk” for honeydew.
Florida Harvester Ant (Pogonomyrmex badius)
This specific harvester ant, native to the southeastern United States, constructs large, conical mounds that can be over 3 feet in diameter. They surround the mound with a distinctive “disk” of excavated sand and fine gravel. The colony’s extensive underground tunnels and chambers can extend over 10 feet deep.
Mound Ant (Formica forsslundi)
This species is a dedicated mound-builder, often found in northern coniferous forests. They construct substantial mounds from a mixture of conifer needles, twigs, and soil. These structures are highly durable and can persist for many years, becoming permanent features of the forest floor and providing warmth for the colony in cool climates.
Saharan Silver Ant (Cataglyphis bombycina)
While their mounds are often low and inconspicuous, these ants are remarkable for their adaptations to extreme heat. They build simple crater-like nest entrances in the desert sand. Their primary architectural feat is the underground nest itself, which provides refuge from the blistering surface temperatures where they forage during the day’s hottest hours.
Black Carpenter Ant (Camponotus pennsylvanicus)
Carpenter ants are known for excavating wood, but they do not build traditional soil mounds. Instead, they push out the sawdust-like frass from their galleries in tree stumps or logs, creating piles that resemble small, unstructured mounds at the base of the wood. This “frass mound” is a clear sign of an active nest within.
Turf Ant (Lasius neoniger)
Common in North America, these ants build small, conical soil mounds in open, sandy areas like lawns, pastures, and golf courses. Their nests are often marked by a single, central entrance hole at the peak. While the mounds are modest in size, they can be numerous, creating a pockmarked appearance in the turf.
Larger Yellow Ant (Lasius interjectus)
Also known as the Citronella Ant for its lemony odor, this species builds its nests in soil, often against foundations or under rocks. Their mound-building is most evident when they perform their seasonal “swarming” flights, when they push large piles of fine, light-colored soil out of their nest entrances to create exit holes for the reproductive alates.
Trap-Jaw Ant (Odontomachus coarctatus)
Some species of Trap-Jaw Ants build nests in the soil marked by small, crater-like mounds. The entrance is typically a simple hole surrounded by a ring of excavated soil. Their architectural efforts are modest, but the mound serves as the entrance to a subterranean nest where they raise their young and store prey.
Funnel Ant (Aphaenogaster pythia)
This species, found in the southeastern United States, is named for the distinctive funnel-shaped entrance to its nest. The ants excavate soil, creating a small, symmetrical crater that funnels down to the main nest entrance. These structures are often found at the base of trees or in open, sandy soil.
Marauder Ant (Carebara diversa)
While they are nomadic raiders, Marauder Ants establish semi-permanent central nests. These nests are often located in the soil or in rotten wood and are marked by large, irregular mounds of excavated earth. The mounds can be substantial, reflecting the enormous size of their colonies, which can contain over 50,000 workers.
Big-headed Ant (Pheidole megacephala)
This invasive species often builds nests in the soil, creating small, irregular craters or mounds, particularly in sandy or loose soils. The mounds are typically unstructured piles of excavated grains of soil and are a common sight in disturbed habitats, gardens, and greenhouses where this ant has taken hold.
Meat Ant (Iridomyrmex purpureus)
A dominant Australian species, Meat Ants are known for building large, domed mounds, often in open, sunny areas. They cover the mounds with small gravel and pebbles, which absorb heat from the sun. These gravel-covered nests can be extensive and are connected by well-defined trunk trails to foraging trees where they tend sap-sucking insects.
Jack Jumper Ant (Myrmecia pilosula)
This Australian ant, known for its powerful sting, builds simple but distinctive nests in the soil. The entrance is typically surrounded by a semicircular or crescent-shaped mound of excavated soil, often with a single, clear entrance hole. The mound is usually not large but is a clear indicator of the presence of a potentially aggressive colony.