Updated on May 3, 2023
Ants make up a huge portion of the fauna on this planet and live on every continent except for Antarctica. You’ll find many types of ants from California to Florida and even Alaska. They’re found in the fossil record and have barely changed over millions of years.
Oddly enough, however, this lack of overall change has still led to an organically diverse group of insects with sometimes surprisingly complex cultures and a striking amount of variation in size and shape – sometimes within a single species.
But something that has fascinated people perhaps even more than the ants are their mounds.
Now, let’s be perfectly clear here: the term “ant mound” can mean a couple different things. For some, it’s a reference to the visible mounds above a nest. For these people, mounds can be big or small, sometimes rising into massive ant hills.
However, for others, including many myrmecologists (those who study ants), the term instead refers to the nest itself when below ground, with “ant mound” referring to above-ground nest sections. Let’s take a look at different types of ant mounds, using both of these definitions.
Types of Ant Mounds
#1 – Allegheny Mound Ant Mound
The Allegheny mound ant (Formica exsectoides) is a field ant that’s earned its name. These ants build huge mounds up to three feet tall and six feet across out of excavated soil. During the construction process, they actively destroy nearby vegetation to ensure the mound won’t be damaged.
Despite the novelty of seeing such huge mounds in the US, it’s best to steer clear, as Allegheny mound ants are highly aggressive if their nest is disturbed.
#2 – Ant Bed
An ant bed isn’t where an ant sleeps, but rather the name of the little pile of debris surrounding the entrances to a nest. These little barriers serve a very real function, providing a fortification around the entrance that helps prevent flooding and other dangers.
They’re often made of excavated materials such as clay, pebbles, sand, or soil, but may also include harvested materials including manure, pine needles, or even use urine as a mortar.
The bed is built with new materials placed at the top to tumble outwards, preventing debris from falling back into the nest. Over time, rain can make these beds harden, at which point they may begin to grow into ant hills.
#3 – Ant Hill
When you think of ants, you might think of huge mountains of earth from which thousands of ants pour, but this is usually far from the truth.
Some ants do indeed built mounds large enough that we call them ant hills, but quite often these are either termite mounds or very old hills. These hills sometimes become extensions of the colony itself, containing its own series of chambers and tunnels.
It’s almost unheard of to find a full-sized ant hill in the US, although they’re far more common in Africa and South America. Why is this?
Simply put, ant hills are ant mounds that have been expanded over hundreds or even thousands of generations of ants. As the colony ages and grows, more and more debris is collected at the entrances, causing the mounds to eventually reach several feet in height.
Related: 15 Ways to Get Rid of Ant Hills
#4 – Argentine Ant Mound
One of many invasive species, the Argentine ant (Linepithema humile) is also one of many species that have multi-queen colonies and an aggressive disposition. Thus, they can end up with extremely large colonies, which break off into satellites as needed.
This means that you’ll likely find a number of mounds within a radius of the parent mound, with ants often traveling between mounds as needed.
The mound itself is generally made of loose soil, although their nesting habits mean you may not always see mounds. For example, they prefer building shallow nests in cracks and crevasses, which may or may not result in debris. You’ll also find them nesting in loose leaf litter or under stones.
They’re also known to take over the abandoned nests of other ant species. Because of how stable their genetics are, it’s common for Argentine ants of one colony to peacefully intermingle with those of other nearby colonies, resulting in super colonies.
#5 – Carpenter Ant Mound
When you think of carpenter ants (Camponotus spp.), you likely picture ants digging through your walls. But don’t mistake them for termites as these ants don’t actually consume wood and instead subsist entirely on liquids. They prefer damp, dead wood and are valuable help when it comes to decomposing rotting wood.
Depending on the species, carpenter ants build their nests either completely in wood or (especially in the case of fallen logs) partly in the wood and partly the ground beneath. The ants create special vents on the side of their nest called kick holes.
They use these holes to kick the indigestible wood pulp and ant frass out of the nest, resulting in piles that resemble sawdust. Inside the home, these piles are often the first indication of a carpenter ant infestation.
#6 – Fire Ant Mound
Fire ants (Solenopsis spp.) are native to South America, but some species have found their way further north, including the infamous Red Imported Fire Ant (Solenopsis invicta).
They have a rather peculiar mound structure made of loose materials that can reach as high as 16 inches tall in lighter soil with heavier soils resulting in mounds as high as 42 inches tall and nearly five feet wide for mature colonies.
What makes these mounds even more curious is the fact that the fire ants don’t generally build them. You’ll see fire ant mounds in open spaces such as lawns or fields. Fortunately, a good fire ant killer works wonders on their mounds.
Under normal circumstances, fire ant nests are located underneath cover, such as logs, masonry, or stones. In these cases, the fire ants prefer moist soils where it’s easier to tunnel.
#7 – Harvester Ant Mound
The term harvester ant actually applies to any ant species that harvests seeds or mushrooms. As such, their mounds can vary in size and shape. However, while some hide their nest entrances under debris, others create visible mounds.
#8 – Pavement Ant Mound
Pavement ants build small to medium-sized ant hills that can be found in the cracks of sidewalks, driveways, and other pavement surfaces. These mounds are made up of soil and sand particles and are usually no more than a few inches in diameter.
This type of mound can be identified by the presence of worker ants moving in and out of the mounds. And these mounds on your sidewalk can number in the dozens as a single colony can have between 3,000 to 10,000 individual ants and multiple queens.
#9 – Pyramid Ant Mound
Pyramid Ants (Dorymyrmex spp.), also known as cone ants, generally don’t have very large colonies and tend to be completely docile. They’re known for their more pointed thorax and the rotting coconut smell they give off when crushed.
As they tend to prefer warmer climates, they’re generally adapted to life in sandier or drier soils.
A pyramid ant mound is conical in shape, with a single entrance and a central crater that acts as ventilation. This gives their mounds a volcanic appearance.
However, this is one of many genera of ants that are known to invade homes, meaning the invading colony won’t have a visible mound unless they’re trailing in from an outdoor colony. Strategically placed ant traps are usually the best line of defense against pyramid ants, sugar ants, thief ants, and pavement ants.
#10 –Texas Leafcutter Ant Mound
Move over Texas Chainsaw Massacre and make way for the Texas leafcutter ant (Atta texana)! Obviously, this type of ant is found in Texas but it’s also known to be in Louisiana and other nearby states.
These agricultural ants harvest leaves to take back to their nests, which they use to cultivate fungus farms. A single colony can have as many as two million workers and is capable of completely defoliating a citrus tree within 24 hours.
Their mounds further illustrate this ruthlessness, as a single nest can have up to 1,000 entrance holes. Much like pyramid ants, the mounds are roughly shaped like a volcano, measuring anywhere from five to 14 inches tall and at least 12 inches across.
The mounds are closely packed together, allowing for the ants to decimate nearby greenery with maximum efficiency.
#11 – Wood Ant Mound
Wood ants belong to the subgenus Formica rufa, named after the red wood ant. They’re rather famous for their ant mounds, which are made up of debris, grass, or needles.
These can reach impressive heights, with the Scottish wood ant (Formica aquilonia) having mounds as high as 8.2 feet tall! Formica polyctena also builds massive mounds out of buds, pine needles and sap.
This latter species is especially fascinating because the mound is designed to keep the nest at a stable temperature. Not only does the amount of material in the mound insulate the nest, but it also decomposes into natural compost.
During decomposition, the internal temperature increases due to the microbial activity occurring. This heat then funnels down into the nest itself. Ensuring the ant larvae are well incubated. As the inner material becomes fully broken down, the ants add more to the exterior to continue this composting process.
#12 – Yellow Meadow Ant Mound
The yellow meadow ant (Lasius flavus) prefers to conceal its nests in living vegetation and will frequently make their homes in lawns and meadows. In a pinch, they’re also known to nest under rocks or other cover.
They build mounds which can be as high as 20 inches, but what’s curious is the way these mounds are both hidden in the grass and easily spotted.
This is because yellow meadow ants are ranchers. They breed root-eating aphids in their nests which feast upon the grasses above, providing the ants with honeydew and are sometimes harvested as food during the winter.
The result is a growing ring of dead ground around the nest, yet any grass that overgrows the mounds will be left untouched.
Morgan is a certified entomologist and pest control consultant and a member of the National Pest Management Association.
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